PULSE OXIMETER
DISPLAY SYSTEM
Project Proposal Feasibility Report
Nick McKee, Benjamin Wohl, Taylor DeHaan, Scott Block
ENGR 339 Seni or Design Project, Ca lvin College
© 2014, Nick McKee, Benjamin Wohl, Taylor DeHaan, Scott Block and Calvin College
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1
Executive Summary
The PODS wrist pulse oximeter will reduce the risk of pilots succumbing to hypoxia while flying at high
altitude. The problem with current pulse oximeters is that they are bulky and are worn on the finger,
disincentivizing pilots to wear them during an entire flight. PODS’ pulse oximeter and warning system
seeks to passively monitor a pilot’s oxygen level through reflectance oximetry and then warn a pilot when
they are in danger of not having enough oxygen in their body. This team of four Electrical and Computer
Engineers has created a basic pulse oximeter prototype and business plan to deliver this highly marketable
and valuable product. Given the current market value for pulse oximeters stands at 1.6 billion yearly and
the size of the pilot market is over 600,000 people, it will take about 3,265 units at $500 each to be a
profitable company in its first year. This equates to roughly 0.1% of the pulse oximeter market and 0.5%
of pilots. This data plus the success in prototyping has lead PODS to determine that this product is
marketable and feasible.
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Table of Contents
1
Executive Summary.....................................................................................................................2
2
Introduction ................................................................................................................................7
3
2.1
Project Description ..............................................................................................................7
2.2
Need for Solution.................................................................................................................7
Project management ....................................................................................................................7
3.1
4
Team organization ...............................................................................................................7
3.1.1
Team members.............................................................................................................7
3.1.2
Advisors ......................................................................................................................8
3.2
Meeting Times.....................................................................................................................8
3.3
Schedule .............................................................................................................................9
3.4
Budget ................................................................................................................................9
3.5
Method of Approach ............................................................................................................9
3.5.1
Stage One ....................................................................................................................9
3.5.2
Stage Two.................................................................................................................. 10
3.5.3
Stage Three ................................................................................................................ 10
Design ...................................................................................................................................... 10
4.1
System Architecture ........................................................................................................... 10
4.1.1
Probe ......................................................................................................................... 10
4.1.2
Amplifier and Filter .................................................................................................... 11
4.1.3
Analog to Digital Converter ........................................................................................ 11
4.1.4
Microprocessor........................................................................................................... 11
4.1.5
Display Driver............................................................................................................ 12
4.1.6
Display ...................................................................................................................... 12
4.1.7
Speaker...................................................................................................................... 12
4.2
Design Norms.................................................................................................................... 12
4.3
Design Criteria .................................................................................................................. 13
4.3.1
Ergonomics ................................................................................................................ 13
4.3.2
Display System .......................................................................................................... 14
4.3.3
App Development....................................................................................................... 14
4.4
Design Alternatives............................................................................................................ 14
4.4.1
Oximetry.................................................................................................................... 14
4.4.2
Display Connection .................................................................................................... 15
3
4.4.3
4.5
5
6
7
Physical Device (Probe).............................................................................................. 16
Design Decisions ............................................................................................................... 17
4.5.1
Microprocessor........................................................................................................... 17
4.5.2
Analog to Digital Converter ........................................................................................ 18
Operations ................................................................................................................................ 20
5.1
Legal form of Ownership ................................................................................................... 20
5.2
Company structure ............................................................................................................. 20
5.3
Decision making authority .................................................................................................. 20
5.4
Significant compensation and benefits packages .................................................................. 20
Industry Profile and Overview.................................................................................................... 21
6.1
Industry background and overview...................................................................................... 21
6.2
Major Customer Groups ..................................................................................................... 21
6.2.1
Aviation ..................................................................................................................... 21
6.2.2
Military...................................................................................................................... 21
6.2.3
Medical...................................................................................................................... 21
6.2.4
Emergency Response Units ......................................................................................... 21
Business Plan ............................................................................................................................ 22
7.1
SWOT Analysis................................................................................................................. 22
7.1.1
Strengths .................................................................................................................... 22
7.1.2
Weaknesses................................................................................................................ 22
7.1.3
Opportunities ............................................................................................................. 22
7.1.4
Threats....................................................................................................................... 22
7.2
Marketing Strategy ............................................................................................................ 22
7.2.1
Demographics ............................................................................................................ 22
7.2.2
Customers' motivation to buy ...................................................................................... 23
7.2.3
Market size and trends ................................................................................................ 23
7.2.4
Advertising and promotion .......................................................................................... 23
7.2.5
Plans for generating publicity ......................................... Error! Bookmark not defined.
7.3
Competitive Analysis ......................................................................................................... 24
7.3.1
Existing Competitors .................................................................................................. 24
7.3.2
Potential Competitors.................................................................................................. 25
7.3.3
Market Survey............................................................................................................ 25
7.4
Cost Estimate .................................................................................................................... 25
4
7.4.1
Development Costs ..................................................................................................... 25
7.4.2
Fixed Costs ................................................................................................................ 26
7.4.3
Variable Costs ............................................................................................................ 26
7.5
Feasibility ......................................................................................................................... 26
7.5.1
Income Statement ....................................................................................................... 27
7.5.2
Balance Sheet............................................................................................................. 27
7.5.3
Cash Flow Statement .................................................................................................. 27
7.5.4
Break-even Analysis ................................................................................................... 27
7.5.5
Ratio Analysis ............................................................................................................ 27
8
Testing ..................................................................................................................................... 27
9
Conclusion................................................................................................................................ 30
10
Acknowledgements ............................................................................................................... 31
11
References ............................................................................................................................ 32
12
Appendix 1: Maxim MAX1416 Data Sheet ............................................................................. 33
5
Table of Figures
Figure 1. Level 1 Block Diagram ....................................................................................................... 10
Figure 2. Company Structure ............................................................................................................. 20
Figure 3. Test Circuit ........................................................................................................................ 28
Figure 4. SPI SCLK Signal Measured During a Transaction ................................................................ 29
Table of Tables
Table 1. Work Breakdown Schedule ....................................................................................................9
Table 2. Bluetooth/WiFi/ZigBee Comparison Summary ...................................................................... 15
Table 3. Microprocessor Decision Matrix ........................................................................................... 18
Table 4. Analog to Digital Converter Decision Matrix......................................................................... 19
Table 5. Finger Device Decision Matrix ............................................................................................. 19
Table 6. Development Cost ............................................................................................................... 25
Table 7. Fixed Cost........................................................................................................................... 26
Table 8. Variable Cost ...................................................................................................................... 26
Table 9. Income Sheet....................................................................................................................... 34
Table 10. Statement of Cash Flow ..................................................................................................... 34
Table 11. Break Even Analysis .......................................................................................................... 36
Table 12. Ratio Analysis ................................................................................................................... 37
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2 Introduction
2.1 Project Description
The Pulse Oximeter Display System (PODS) team’s project seeks to solve the problem of pilots in
unpressurized airplanes crashing due to hypoxia. This project will provide a remedy to the problem by
creating a pulse oximeter to monitor a pilot’s oxygen levels throughout flights and issue warnings if they
are in danger of becoming hypoxic. A few constraints include: designing the oximeter to be comfortably
worn for hours at a time and not interfere with the pilot’s range of motion or use of hands, the system
displaying the oxygen levels, pulse, etc. must be able to be easily seen by the pilot and provide visual and
auditory warnings when oxygen levels get too low.
2.2 Need for Solution
Each day pilots put their lives at risk launching their airplane into the sky. These risks include
technological failures and weather hazards, among many others. There is one risk, however, that pilots
easily overlook: hypoxia. Hypoxia is a condition where the body lacks adequate oxygen to function
properly leading to impaired judgment and loss of consciousness. The FAA states that pilots flying above
10,000 feet must be on some form of oxygen, but this regulation fails to account for two crucial factors:
the exact altitude when hypoxia begins to onset in a pilot; and if a pilot is getting sufficient oxygen
through their oxygen supply. Low oxygen levels at high altitude affect each person differently based on a
variety of factors, including fitness level or tobacco use, putting some at risk of becoming hypoxic before
10,000 feet. It stands to reason that all pilots should have access to a device that measures the level of
oxygen in their blood. Furthermore, this device must be comfortable to wear and not inhibit a pilot’s
dexterity in any way. Finally, this device should clearly display and issue a warning when a pilot is in a
potentially dangerous situation.
3 Project management
3.1 Team organization
The team consists of four senior engineers in the electrical and computer concentration. The project is
divided into separate tasks and each member of the group is in charge of a different part of the project.
3.1.1
Team members
Nick McKee: Nick is an electrical/computer engineering concentration from Arlington Heights, Illinois.
He has also been a four-year member of the Calvin College Cross Country team and also of the Calvin
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College Track and Field Team. He has experience working as a controls engineer intern. He has been
assigned the task of researching business components of the project.
Taylor DeHaan: Taylor is a senior electrical/computer engineering student from Excelsior, Minnesota.
Taylor has interned for Seagate Technology in Bloomington, Minnesota over the summer of 2013 and
again in Longmont, Colorado over the summer of 2014. He is currently continuing his work from the past
summer in a part-time intern position and has accepted a permanent role in the Advanced Storage
Development team at Seagate starting the summer of 2015. Taylor’s role in team consists of lead
research, system design, and team webmaster.
Benjamin Wohl: Benjamin is an electrical/computer engineering concentration student from Canton,
Michigan. He is a four-year starter and captain of the Calvin College baseball team. He has been assigned
the task of researching the display unit as well as developing team posters and presentations throughout
the course of the project.
Scott Block: Scott is an electrical/computer engineering concentration student from Grand Rapids,
Michigan. The past 8 years of his life have been spent serving in the military with two overseas tours to
Iraq and Afghanistan. As a software engineering inter, Scott worked at Visteon Corporation during the
summer of 2014. He was tasked with researching the microcontroller and editing the team’s work.
3.1.2
Advisors
The team’s main advisor is Professor Mark Michmerhuizen. He received his BSE from Calvin College
and went on to obtain his MSEE from the University of Michigan and his MBA from Grand Valley State
University. He worked in industry for 22 years before joining the staff at Calvin College. Professor
Michmerhuizen mainly aided the team by giving feedback on design ideas and by giving professional
advice.
The team was also in contact with Taylor’s father, Doug DeHaan, a private pilot and avid aviation
enthusiast. He originally proposed the project idea to the team after seeing a tangible need for the device
in private aviation. Throughout the year, he has provided specifications and possible features for the
device and has provided input from other pilots on the project.
3.2 Meeting Times
The team normally meets at 1:00 pm each Monday. At this time, tasks are divided up and all relevant
information is communicated to each member. The team also meets from 2:30 pm till 3:20 pm every
Monday, Wednesday and Friday for the regularly scheduled senior design class time. All other meeting
times are scheduled as necessary.
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3.3 Schedule
See Table 1 below for the team’s schedule.
Table 1. Work Breakdown Schedule
Task Name
Duration
S tart
Finish
Fall 2014
44 days
Wed 10/8/14
Mon 12/8/14
Oral Presentation
Project Brief for
Industrial consultant
Project website
Project poster
PPFS
Introduction
Background & Research
Scope
Design Criteria
Design Alternatives
Feasibility
Cost/budget
Schedule
Business plan
Conclusion/review
Appendix
Rough draft
Review/polish PPFS
2 days
6 days
Fri 10/10/14
Wed 10/8/14
Mon 10/13/14
Wed 10/15/14
7.5 days
8 days
44 days
1 day
1 day
2 days
3 days
2 days
1 day
1 day
1 day
1 day
1 day
1 day
24 days
5 days
Mon 10/13/14
Wed 10/22/14
Wed 10/8/14
Wed 10/8/14
Thu 10/9/14
Fri 10/10/14
Tue 10/14/14
Fri 10/17/14
Tue 10/21/14
Wed 10/22/14
Thu 10/23/14
Fri 10/24/14
Mon 10/27/14
Tue 10/28/14
Wed 10/8/14
Tue 11/11/14
Wed 10/22/14
Fri 10/31/14
Mon 12/8/14
Wed 10/8/14
Thu 10/9/14
Mon 10/13/14
Thu 10/16/14
Mon 10/20/14
Tue 10/21/14
Wed 10/22/14
Thu 10/23/14
Fri 10/24/14
Mon 10/27/14
Tue 10/28/14
Mon 11/10/14
Mon 11/17/14
Predecessors
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13
18
21
22
23
24
25
26
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3.4 Budget
The team was allotted an initial budget of $500 dollars for prototyping and other peripherals to the
project. Thus far, the team has procured a Raspberry Pi and its necessary accessories (i.e. memory card,
break out wires, and power supply), a high resolution analog to digital converter, various LEDs, and
photodiodes. The accrued amount spent on these components is $72 leaving $428 left in the budget for
future prototyping.
3.5 Method of Approach
3.5.1
Stage One
The team will research the pulse oximetry industry and current products available to consumers. This
research includes looking into design alternatives. This is also when the selection of which components to
use for the different aspects of the project takes place.
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3.5.2
Stage Two
The team will focus on getting all the individual components of the project working. This involves
building a bench top prototype to make sure that all of the components will work together. This stage is a
transitional stage between one and three.
3.5.3
Stage Three
The team will integrate the different aspects of the bench top prototype into one working model. This
model and the final design report will serve as the final deliverable for this project.
4 Design
4.1 System Architecture
In the following sections, the system architecture is broken down into individually described components.
Below is a Level 1 block diagram of the system.
Figure 1. Level 1 Block Diagram
4.1.1
Probe
The probe component seem above consists of light-sources and photo sensor. The light sources will be the
emitters of red and infrared light needed for pulse oximetry, the non-invasive measurement of blood
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oxygen saturation. The light emitters will require a source of power and could be controlled by the
microprocessor used in the system in order to manage the amount of power expended. The photo sensor
in the probe will measure the light transmitted through or reflected off of the user’s skin. The light seen
by the sensor is used to calculate oximetry data. The sensor is connected to the amplifier used in the
system. On the mechanical side, the probe, in addition to housing the light-emitters and the photo sensor,
will be able to be comfortably worn by the user while maintaining the proper contact required to measure
oximetry data.
4.1.2
Amplifier and Filter
The signal from the probe’s photo sensor is amplified so that the appropriate signal processing can be
accomplished. The amplifier will be multi-staged, with a minimum of a voltage amplification stage and
an output stage. Additionally, an active or passive low pass filter network will be designed in order to
eliminate unwanted noise. The interface between the amplifier and the probe will consist of a ground and
signal wire. The amplifier and filter will also require a power source and will provide the amplified signal
to the analog to digital converter.
4.1.3
Analog to Digital Converter
The analog to digital converter takes the continuous amplified and filtered analog signal and converts it to
a discrete-time digital signal for processing. The converter’s specifications - such as resolution, sampling
frequency, bandwidth, and accuracy - must be appropriate for the range of signals produced by the
amplified and filtered photo sensor. Like the probe and amplifier, the analog to digital converter requires
a power source and interfaces with the amplifier and filter system component through ground and signal
wires. The converter outputs a series of logic level wires proportional to the resolution of the converter.
4.1.4
Microprocessor
The system’s most vital component, the microprocessor, will perform all the processing of the oximetry
data in order to produce graphical representations for blood oxygen saturation and heart rate.
Additionally, the microprocessor runs the algorithms designed to monitor the user’s blood oxygen
saturation and issue warnings when blood oxygen saturation level drops below the specified threshold.
The microprocessor is also the most flexible component of the system as there are numerous different
features that can be found in microcontroller packages. The important aspects to consider when selecting
a microcontroller are: price, power consumption, number and type of inputs and outputs (I/O), and
application suitability. Other factors which are not required but add desirability are: built in analog to
digital converter, integrated antenna, Linux based operating system, and pre-programmed communication
protocols.
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4.1.5
Display Driver
The display driver’s purpose in this system is to take the output from the microprocessor intended for the
display and generate the appropriate signals to make the display show the intended graphics. At a high
level, the display driver interfaces between the display and the microprocessor. The display driver may
likely be built into the display used for this system.
4.1.6
Display
The display provides a visual for the data, graphics, and warnings as well as any other necessary
information to the user. The display must be of an appropriate size/resolution in order to accurately
display the information from the microprocessor such as graphing of heart rate or blood oxygen
saturation. On the physical side, the display will be able to withstand a fair amount of abuse and must
have a mounting system similar to that of modern GPS allowing the pilot place it to suit his needs. The
display also requires a power supply in the form of a rechargeable battery or a wired plug in power
supply. The display interfaces with the processor through either a wired connection or wirelessly through
a receiver.
4.1.7
Speaker
The speaker provides auditory warnings to the pilot when triggered by the microprocessor. The speaker
must be loud enough to combat the noises found the cabin of a small aircraft and be clearly
distinguishable from other possible warnings from the airplane itself (i.e. stall warnings, autopilot
disengage, et al). The speaker interfaces with the microprocessor and will be housed in either the display
or microprocessor module.
4.2 Design Norms
Trust
“Design should be trustworthy, dependable, reliable, and avoid conflicts of interest”
Due to safety being the primary goal of this project, the design norm of Trust is paramount. This project is
frivolous without a pilot putting their trust into using the device to correctly measure, monitor, and
communicate blood oxygen levels to prevent hypoxia. Furthermore, this trust encompasses all levels of
design, production, and application; with potential life and limb at risk, all aspect of the device must be
dependable, safe, and reliable in many circumstances and environments since a malfunction could result
in danger for the user. Finally, the reliability of the device is extremely important since the task of flying
an airplane is a demanding and often stressful process. Therefore, the pilot should not have to worry the
device is functioning properly and trust in it if it could fail at a crucial time.
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Transparency
“Full disclosure both in the design process and to the public, regarding options, effects, defects, and
tradeoffs.”
Similar to the design norm of Trust, the norm of Transparency is crucial to this project. In order to
establish trust with the users, all relevant details of the project must be disclosed. If any defects are
discovered, these absolutely must be disclosed since a failure to do so could result in fatal crashes. Also,
all effects of the device the user’s ability to operate an aircraft be must be disclosed immediately in order
to stay true to the project’s core goal of preventing crashes. Finally, transparency includes providing the
performance tests and corresponding results to identify the limitations and feasibility of application for
this device under different circumstances. Disclosing as much relevant information as possible contributes
the user’s sense of security thus building a relationship of trust.
Integrity
“Design should have completeness, harmony of form and function, promote human values and
relationships, and be pleasing and intuitive to use”
The final design norm identified for this project is Integrity. This design norm offers the user closure and
value when using the device. Closure in the sense that it was created with them in mind to relieve the
mental burden of having to worry whether the device is functioning properly and value through keeping
them safe by using an intuitive and well thought-out interface. The design norm of Integrity heavily
affects the design of the user interface on the display system as the norm dictates that the interface must
be both pleasing to use and highly functional. The design norm of Integrity also complements the design
criteria of ergonomics and dictates that the ergonomics of the device should also be balanced with its
functionality. With these considerations in mind, the device will be the very example of integrity.
4.3 Design Criteria
4.3.1
Ergonomics
The design of the pulse oximeter must be comfortable and easy to wear. If it is a hassle to put on or wear,
pilots will not be as likely to buy or use it. The design is going to focus on making the pulse oximeter into
a small band that is worn around the w. This will allow for pilots to have a full range of motion in their
hands and fingers, a large improvement over the current pulse oximeters on the market. This new pulse
oximeter will be comfortable for pilots to wear from takeoff to landing.
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4.3.2
Display System
The display system for this product focuses on simplicity and ease of use. The most critical times for
display are when a pilot is starting to suffer from symptoms of hypoxia. If a pilot becomes confused, this
system must display the data in an easy to understand way so its interpretation is comprehensible. The
display is being designed to be a small touch screen device that could be mounted in a convenient place in
the cockpit. The warning system will be based on the level of oxygen in the blood. This data will be
received from the finger worn pulse oximeter and transmitted to the warning system. This system will
then give out status messages to the pilot. The warning system will measure the change in blood oxygen
levels in an effort to predict hypoxia and give warnings before the pilot reaches a critical state.
4.3.3
App Development
The app would either take the place of the display system or work alongside it. We are hoping that it will
be able to display the same data that would be shown on the display screen. Having the display system on
an app will lower the cost of development and the cost of the finished product.
4.4 Design Alternatives
4.4.1
Oximetry
A pulse oximeter is an electronic device which measures blood oxygen saturation non-invasively. This
method is effective at determining oxygen saturation as it utilizes “the light absorptive characteristics of
hemoglobin and the pulsating nature of blood flow in the arteries to aid in determining the oxygenation
status in the body” 1 . In addition to the LEDs and photodiodes, a pulse oximeter also employs a number of
other components, most notably: a microprocessor, analog to digital converters, digital to analog
converters, a display system, and amplifiers. When designing an oximeter, they are two different methods
of measuring blood saturation which must be examined.
4.4.1.1
Transmittance Oximetry
A transmittance pulse oximeter measures blood oxygen saturation by producing two beams of light at
different wavelengths (red and infrared) via light-emitting diodes (LEDs) and by measuring the light
transmitted through the user’s fingertip via photodiodes1 . Transmittance pulse oximeters make up the
vast majority of consumer pulse oximeters.
1
(Oximetry n.d.)
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4.4.1.2
Reflectance Oximetry
A reflectance pulse oximeter also produces two beams of light but instead of measuring the light
transmitted through the user’s skin, it measures the light reflected by the user’s skin. From a design
perspective, the primary difference between the two is that a reflectance pulse oximeter does not require a
thin section of the user’s body in order to obtain measurements. A recent study on the differences of
transmittance and reflectance pulse oximetry published in the Anesthesia & Analgesia Journal showed
that both methods were equivalent in accuracy and performance 2 .
4.4.2
Display Connection
4.4.2.1
Wired
One option for connecting the oximeter sensors and circuitry with the digital display system is using a
hardwired connection. The benefits of using a hardwired system include: low-cost, no speed restriction,
no additional power consumption. Drawbacks of using a wired connection include: vulnerable to fraying
and depredation, potentially could snag on the many controls in a cockpit, could inhibit pilot’s range of
motion, and physically limits the placement of the display system.
4.4.2.2
Wireless
Alternatively to a wired connection, a wireless system could be used in order to connect the oximeter
sensors, circuits, and microprocessor to the display system. Within wireless systems, there are a number
of technologies which must be considered individually, however, there are some benefits that they all
share. A few such benefits include: no limits on the pilot’s range of motion, eliminating the possible
snagging and general physical limitations of wires, overall flexibility. Conversely, a few drawbacks
include: additional power consumption, additional cost, additional complexity and circuit board space. A
table summarizing the details of each of the three wireless technologies described in the proceeding
sections can be seen below.
Table 2. Bluetooth/WiFi/ZigBee Comparison Summary
2
Bluetooth
WiFi (IEE 802.11n)
ZigBee
Operating Frequency (GHZ)
2.4
2.4 and 5
2.4
Range (m)
10
1-100
1-100
System Resources (KB)
250
1,000
4-32
Data Rate (Mb/s)
5.76
600
2
Power Consumption
Medium
High
Very Low
(Wax 2009)
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4.4.2.3
Bluetooth
Bluetooth is a type of wireless technology which utilizes radio frequencies over a spectrum 2.4 to 2.485
GHz in order to achieve wireless communication3 . Bluetooth also uses a technology called adaptive
frequency hopping in order to minimize interference with other radio waves present across its frequency
spectrum. The maximum range of a Bluetooth device is roughly 10 meters3 . When compared to ZigBee
and WiFi, Bluetooth achieves moderate battery consumption4 . Finally, Bluetooth uses about 250 KB of
system resources and has a maximum data rate of 5.76 Mb/s.
4.4.2.4
WiFi (IEE 802.11)
WiFi, also known by the Institute of Electrical and Electronics Engineers (IEEE) standard 802.11 (in the
context of this paper, 802.11n will be used), is a wireless technology which operates in the 2.4 and 5 GHz
bands5 . WiFi, whose primary goal is high data rates, has a maximum data of 600 Mb/s and uses over 1
MB of system resources. WiFi also has a range anywhere from 1 to 100 meters. Although WiFi has very
high speeds, when compared to ZigBee and Bluetooth, it has very high power consumption4 .
4.4.2.5
ZigBee
ZigBee, the final type of wireless technology considered for the proposed design, operates in the 2.4 GHz
frequency band. ZigBee uses between 4 KB to 32 KB of system resources and achieves data rates up to 2
Mb/s4 over a range of 1 to 100 meters. ZigBee, whose primary design features are low-cost and lowpower, has very low power consumption when compared to WiFi and Bluetooth. Another unique feature
of ZigBee, in addition to very low power consumption, is ZigBee’s ability to support extremely large
mesh networks (over 64 devices)4 .
4.4.3
4.4.3.1
Physical Device (Probe)
Headset
The majority of pilots wear some form of headset to eliminate outside noise and communicate with the
tower and other passengers. Reflectance oximetry would lend itself to this design. It is also possible that
with some clever design work, transmittance oximetry could work by putting the sensor in the headset.
The argument for putting the sensor in the headset is that the headset already has a wired connection to
the plane, allowing the design to take advantage of that wire, minimizing the hindrance and danger to the
pilot. The current costs of headsets may prove to be the biggest detriment as researching and prototyping
would be difficult for this project and its budget.
3
(A Look at the Basics of Bluetooth Technology n.d.)
(ZigBee Technology n.d.)
5 (IEEE 802.11 Standards Tutorial n.d.)
4
16
4.4.3.2
Bracelet
A bracelet would take advantage of the reflectance oximetry and could be made large enough to have a
power supply to support wireless capability. It also would not limit the dexterity of a pilot's fingers. The
biggest challenge related to this design is that the bracelet needs to remain comfortable for the whole
flight all while it must maintain good contact with the skin for accurate oxygen readings.
4.4.3.3
Finger Attached
A sensor in a ring or clip on device for the finger is currently available on the open market. This allows
for easier research and prototyping, but may limit the wired/wireless options. The simplicity and small
design of the device lends to comfort and allowing good mobility for the pilot, but also presents heavy
constraints on the size of the device.
4.5 Design Decisions
4.5.1
Microprocessor
When evaluating different microcontroller packages with microprocessors, the team identified 4 key
fields: cost, processing power, hardware flexibility, software flexibility, and size. Cost was considered as
the final design should be at a similar price point to other oximeters currently on the market. Processing
power (clock speed, RAM, graphics processors, etc.), was considered since the microcontroller will need
to run various algorithms for oximetry computation and monitoring in addition to providing a graphical
display. Hardware flexibility was considered since, depending on the final design, the microprocessor
may need to interface with devices like the analog to digital converter through different interfaces and be
able to utilize Bluetooth, WiFi, or ZigBee. Software flexibility was considered since the software for
oximetry measurement and monitoring, graphical interface, and interfacing with hardware may require
various high-level languages and libraries. Finally, size was considered to align with the design criteria of
ergonomics although the microcontroller will most likely be mounted on the external display and thus
will not need to meet the constraints of being wearable. These considerations outlined were placed into a
decision matrix with equal weighing and maximum possible scores of five which can be seen in Table 3
below.
17
Table 3. Microprocessor Decision Matrix
Raspberry Pi B+
Arduino Yun
Jennic JN5148
Cost
3
1
5
Computing Power
5
4
1
Software Flexibility
5
3
1
Hardware Features
5
5
2
Size
2
3
5
Total
20
16
14
As seen in Table 3, the Raspberry Pi B+ was determined to be the best microprocessor package for the
project. One key feature of the Raspberry Pi which distinguished itself from the other considerations was
an onboard graphics processor as this will enable the final design to be able to provide a low latency
graphical display of oximetry readings as well as real time graphs of things like heart rate. Another key
feature of the Raspberry Pi was its status as a single board computer and its subsequent ability to compile
and run high level languages like Python, C/C++, and Java as this will allow the software to be developed
in almost any language desired.
4.5.2
Analog to Digital Converter
When choosing which analog to digital converter (ADC) to use, the team considered the 16-bit, 500
samples/second Maxim MAX1416, the 10-bit, 200k samples/second Microchip Technology MCP3008
and the 12-bit 100k samples/second Microchip Technology MCP3202. One thing to note about the
possible choices identified is that only dual in-line package (DIP) chips were considered they offer the
most flexibility for prototyping on breadboards. The four features considered when evaluating which
analog to digital converter to use included: sampling frequency, resolution, number of channels, power
consumption, and additional features. These features were then scored out of five and placed in a
decision matrix seen in Table 4 below.
18
Table 4. Analog to Digital Converter Decision Matrix
MAX1416
MCP3008
MCP3202
Sampling Frequency
1
5
4
Resolution
5
2
3
Number of Channels
3
5
3
Additional Features
5
0
0
Power Consumption
5
2
2
Total
18
14
12
The result of the decision matrix seen in Table 4 is that the Maxim 1416 ADC is the best choice for the
project. A few of the important categories which it proved to be the best option was in resolution, power
consumption, and additional features. Although 16-bits may be a higher resolution than is needed for the
final design, the team determined that for the prototype, it was best to go with a high resolution as it
provided the most room for data analysis. The MAX1416 proved to be the best choice for power
consumption as, according to its datasheet which can be seen in the appendix, its max power consumption
is 1mW whereas the two Microchip Technology ADCs have a max power consumption of 3mW. Finally,
the MAX1416’s additional features of a programmable gain amplifier (PGA) and digital filtering was key
in distinguishing itself from the other ADCs as these two features eliminate the need for an additional
preamplifier and filter network between the probe and the ADC.
4.5.3
Table 5 below shows the decision matrix for the different physical devices the scores are based off a
maximum score of 5. The decision is based off cost to implement, mobility for the pilot, design aspects
and, size. From this decision matrix it was decided that a Bracelet design is the best option for this
project.
Table 5. Finger Device Decision Matrix
Headset
Bracelet
Finger Attached
Cost
1
3
2
Mobility
4
4
3
Design
3
3
1
Size
3
3
4
Total
11
13
10
19
5 Operations
5.1
Legal form of Ownership
This company will plan to be a limited liability company (LLC). The one main advantage to this form is
the protection from personal liability for business decisions and actions. If the company incurs any debt
along the way, the company’s members are safe in terms of their personal assets. This doesn’t mean that
the members are shielded from other acts of injustice in the workplace. The two other positives of an LLC
is the sharing of profits as the members see fit as well as much less record-keeping compared to other
forms of organization.
5.2
Company structure
Figure 2. Company Structure
5.3 Decision making authority
Each officer will have authority over each of their assigned teams in their department. All final
department decisions will be made by the chief officers. The final decisions of the company will
ultimately rest in the hands of the President, having the final decision making authority.
5.4 Significant compensation and benefits packages
As the PODS company is on the smaller side, the amount of compensation and benefits will be smaller
compared to the larger corporations. A 401K plan will be given to each employee, as well as some
employee stock ownership plans. Employees will also benefit from a total of two weeks paid vacation and
a few allotted sick days.
20
6 Industry Profile and Overview
6.1 Industry background and overview
The first device to measure blood oxygen saturation was developed by Karl Matthes in 1935. This device
is was much more crude and invasive than the simple finger devices on the market today. With a focus on
ergonomics and comfort, the pulse oximeters currently are easy to use and very accurate. The PODS
Company will focus on smaller design and better ergonomics while keeping the accuracy as important as
before. A more intuitive display system is also a major focus.
6.2 Major Customer Groups
6.2.1
Aviation
The initial purpose of PODS was to sell the design or products to airlines that were in need of a better
oximeter display system. The simplicity and ease of using the product would make the older pulse
oximeters obsolete. The design is geared more towards, but not limited to, the private pilots sector of
aviation.
6.2.2
Military
Similar to the private pilots, the air force may be able to use the product in the same manner. There would
need to be some high end adjustments as well as higher quality control for these applications, but they are
a possible consumer of the product.
6.2.3
Medical
The design of the PODS pulse oximeter could prove to be more beneficial to the everyday hospital
patient. The smaller device would cause less discomfort than the bulky finger ones used today, as well as
giving more important information to the nurses and doctors. Once again, the need for a high-end product
would put some pressure on the quality control of the devices sold to the medical field.
6.2.4
Emergency Response Units
The smaller design as well as the wireless display will prove to be much simpler for medical teams in
ambulances to use. Quicker and easier is the whole goal of these units, so the PODS product will be a
clear advantage.
21
7 Business Plan
7.1 SWOT Analysis
7.1.1
Strengths
A strength of the company is the uniqueness of the product. There are no pulse oximeters which are only
worn on the wrist so an opportunity exists to meet that need. Another strength of this company is the
ability to expand the into more than just the target market. The project was designed for the use by a
subsection of pilots but could move into other areas like medical devices.
7.1.2
Weaknesses
One of the weaknesses of this product is that people may not see the need for it. To combat this, a large
amount of resources will go into developing a marketing plan and advertising campaign explaining the
value in measuring blood oxygen saturation and added level of safety wearing it brings. Another
weakness is that it is a start-up company. PODS cannot take advantage of things larger companies have
access to like economies of scale, readily available capital, brand recognition, assets or investment.
7.1.3
Opportunities
There is a large opportunity for this company to grow quickly due to the uniqueness of this product. As of
yet, there is no product out on the market that meets pilots needs in the same way that this does. If this
product demonstrates reliability and improves pilot safety then there will be more opportunities to meet
customers’ needs.
7.1.4
Threats
A large threat is another company getting to market sooner with a similar product. To address this, the
product must get to market as quickly as possible in order to gain the largest chunk of the market. There is
also a risk of larger companies coming into the market with similar products but undercutting PODS’
established price point.
7.2 Marketing Strategy
7.2.1
Demographics
The demographic currently being researched is private pilots who fly non-pressurized airplanes. Another
demographic that we are targeting are charter aviation companies that charter non-pressurized aircraft.
Pilots flying pressurized airplanes are not at high risk to hypoxia but hope to market to them on the basis
of pressurization failures and that it will generally improve their safety.
22
7.2.2
Customers' motivation to buy
Customer motivation to buy this product stems from it being comfortable to wear and improving a pilot’s
safety. These features along with an easy to read display will help a wrist worn pulse oximeter stand out
from others.
7.2.3
Market size and trends
The market for pilots is not incredibly large. It is estimated that there are 617,128 certified pilots in the
United States6 . “...the market for pulse oximeters in the U.S., Asia Pacific and Europe is expected to grow
to over $1.3 billion by 2020. This market includes a range of monitors and sensors including bedside,
handheld and fingertip monitors; disposable and reusable sensors. Market growth can be attributed to cost
savings of reprocessed disposable sensors and the lower price point of consumer pulse oximeters that are
selling well through retail.” 7
7.2.4
Advertising and promotion
7.2.4.1
Message
In order to best market this pulse oximeter system, the focus will be on two main factors: the safety that
comes from wearing the oximeter and the practicality of the design. The emphasis will be on the fact that
wearing a pulse oximeter for the duration of the flight increases pilot safety by reducing their risk to
hypoxia. A secondary emphasis will be placed on how easy the system is to use. The final emphasis will
be on how the pilot will barely notice wearing the device while flying.
7.2.4.2
Media
The target market for this project is a very specific group of people so we plan to market to them mainly
through the use of magazine and internet ads. We will focuses are efforts on AOPA Pilot Magazine,
Flying Magazine, and Plane & Pilot Magazine. As for internet ads, using websites like Google, Amazon
and many aviation retailors should yield the best results.
7.2.4.2.1
Desired imagine in market
This product needs to be affordable to compete with low cost of a finger worn oximeter. With that said,
the number one concern is to make sure that the pulse oximeter is constructed with high quality parts. The
PODS brand should be something that can be trusted in the private aviation industry. It is also understood
6
(Pilot certification in the United States 2014)
(Pulse Oximeter Market Expected to Grow to over $1.3 Billion by 2020 in the U.S., Asia Pacific, and Europe
Combined 2014)
7
23
that aviation in general is a very expensive hobby so pilots might be more willing to spend more money
on a device that will offer them an added level of safety.
7.2.4.2.2
Comparison against competitors’ prices
Most blood oxygen monitoring systems that include an external display are in the range of $1,000 to
$3,000. Most of these machines have more capabilities beyond blood oxygen monitoring. With our price
point of $500 we will be much cheaper than similar medical systems.
7.2.4.2.3
Discount Policy
We will offer a discount policy for any company that buys ten or more devices. We will reduce the price
by a set amount in hopes off incentivizing larger piloting companies to buy our product. As competitors
enter the market we realize that we may have to decrease or price in order to stay competitive. We believe
that we will be able to do this and still make a profit.
7.2.4.2.4
Gross Profit Margin
With the price point set at $500 we anticipate a gross profit margin of 11%, 19% and, 23% for the first
three years of the business.
7.2.4.3
Distribution Strategy
PODS will mainly sell its product through online distributors. We hope to employee at least one sales
person in the next few years whose job it will be to sell packages of our products to larger firms. The
warehouse will be located in the Midwest with easy access to most areas of the United States.
7.3 Competitive Analysis
7.3.1
Existing Competitors
There are two main competitors in this market. The first is Covidien and the second is Masimo. Both of
these companies produce various pulse oximeter devices that are used in health care settings.
7.3.1.1 Covidien
Recently acquired by Medtronic, they are a global healthcare products company and manufacturer.
Covidien was identified by iData Research as battling for the top spot in the global market for pulse
oximeters. Their focus is primarily on oximeters for medical uses such as homecare.
7.3.1.2 Masimo
Masimo is a manufacturer of patient monitoring products and is primarily known for their pulse
oximeters. In 2012, they were the number 1 seller of oximeters to hospitals and was identified as battling
for the top spot in the global market for pulse oximeters. While their primary focus is on oximeters for
24
hospitals, they recently released an oximeter that plugs into smart phones, targeting the aviation and sport
users.
7.3.2
Potential Competitors

Concord Health Supply

SantamedicalTM

Nonin Medical
7.3.2.1
Impact on the Business
Many of these companies have products similar to ours that are used as pulse oximeters for sports and
personal use. These companies have more experience marketing to pilots and also have brand names that
are known and respected in the industry. They each hold a large part of the market and would be hard to
compete with if they came out with a product similar to what PODS has come up with.
7.3.3
Market Survey
A market survey for this product showed many interested buyers. Most pilots use a pulse oximeter
sparingly and if we can design it to not be in the way most will use our product.
7.4 Cost Estimate
7.4.1
Development Costs
Development costs for the project are shown in the table below. These costs are based on the assumption
that engineering jobs cost the company $80 per hour. These costs do not include salaries of employees or
other cost other than costs that are specific to the development of our product.
Table 6. Development Cost
Hours
Specification
Planning
Testing
Electrical Design
Hardware
Electrical Design Software
Marketing
Industrial Design
Prototypes
Total
120
1000
1000
200
1500
100
500
4420
Total
Cost ($)
9600
80000
80000
16000
120000
8000
40000
2000
365600
25
7.4.2
Fixed Costs
Fixed costs for the first year of operation are shown in the table below. The costs are estimates based on
research done by PODS. The research was based off of cost that other small business experience.
Table 7. Fixed Cost
Fixed Costs ($)
Utilities (500 per month)
Salaries
Advertising
Insurance ($30 per month)
Manufacturing
Management
Employee Benefits
Development
Total
7.4.3
6000
240000
10000
360
35100
124650
10000
426110
Variable Costs
Variable costs for the first year of the business are shown in the Table below. These costs are based off
producing 4000 units in the first year.
Table 8. Variable Cost
Variable Cost ($)
500000
Direct Material
200000
Direct Labor
100000
Variable Manufacturing
140400
Employees
360,000
Sales Commission
20000
Shipping
Total 1320400
7.5 Feasibility
From the calculation of the different costs associated with the project it was found that the design is
feasible. From the costs that have been estimated in the previous sections we believe that PODS can be a
profitable company. Over time we hope to reduce the cost of our product after the initial startup loan is
paid back. A Pro-Forma Income Statement and Cash Flow Statement were used to analyze the financial
feasibility of PODS LLC. They are descried in the following sections of the report with the tables
provided in the appendix.
26
7.5.1
Income Statement
At a price point of $500 per unit the company has a net income after tax of $289,530 in the first year. In
the second and third year the company has net income after tax of $611,793 and $862,018 respectively.
7.5.2
Balance Sheet
A balance sheet is not included due to the fact that all inventory is used each year and all good produced
are sold. The assets of the company can be reduced to available cash. The company debt is simply the
bank debt at 10% interest rate while the equity is the original $50,000 invested in the company by the
owners.
7.5.3
Cash Flow Statement
From the cash flow statement PODS has decided to only reinvest what is needed for working capital and
to use the remaining profits to pay off company debt. This will help the company to reach its goal of
paying off its bank debt in six years.
7.5.4
Break-even Analysis
At the ideal price point for our product 3,265 units need to be sold in the first year to break even. This
equates to 1,632,104 dollars of sales. After the first year, the number of units that need to be sold to break
even decreases due to the high startup design cost of the company. The break even sales volumes for year
two and three are $1,168,284 and $1,070,851, respectively.
7.5.5
Ratio Analysis
The ratio analysis is detailed in the appendix section of this report. From this it can be seen that the profit
margin for the first three years of the company’s life are 11%, 19% and, 23% respectively. This shows
that we be able to pay off bank debt and cover expensive that the company may encounter.
8 Testing
After choosing the ADC and microprocessor to use for the project, the team procured the two components
and began working on building a system on a breadboard. This system consisted of the ADC, a
phototransistor, and the Raspberry Pi. The goal of this system is to convert the data from the
phototransistor via ADC and sample, analyze, and graph the digital data with the Raspberry Pi. Testing
this involved designing a basic phototransistor circuit, building the circuitry for the ADC, and setting up
and working out the bugs on the serial peripheral interface (SPI) between the Raspberry Pi and the ADC.
Additionally, testing involved developing basic software to read in the data from the Raspberry Pi’s SPI
port for graphing. A picture depicting the circuit built can be seen in Figure 3 below.
27
Figure 3. Test Circuit
The team successful in getting the SPI working on the Raspberry Pi and sending data over SPI and read it
back in a closed circuit. The team successfully build a phototransistor circuit and observed the change in
current output from the transistor as it received different levels of light. Finally, the team successfully
implement a Python script which read in SPI data and generated an animated graph. At this point,
however, the team was not able to get the ADC to work.
Debugging for the ADC was performed by measuring the voltages on the different pins such as GND,
VDD, VREF-, VREF+, etc. and ensuring these were appropriate per the datasheet. The team then began
debugging the SPI connection between the ADC and the Raspberry Pi by probing the master in slave out
(MISO), master out slave in (MOSI), serial clock (SCLK), and slave select (SS) pins with an
oscilloscope. For these experiments, the oscilloscope was adjusted so that it trigged on a falling edge
voltage of 1.1v (selected as it is between 3.3v and 0v) in order to capture the signals on the 4 different SPI
pins. A picture of the signals found on the SCLK during one SPI transaction can be seen in Figure 4. In
particular, measuring the signal on the SCLK during a SPI transaction proved helpful as the team
determined that, based on the timing diagram found on the ADC’s datasheet, the SPI mode was not set
correctly. The team rectified this situation be changing the SPI mode on the Raspberry Pi to match the
mode required by the ADC. Despite this discovery, the team was still not able to get the ADC to work
and is currently continuing to debug the system.
28
Figure 4. SPI SCLK Signal Measured During a Transaction
29
9 Conclusion
PODS sees the wrist worn pulse oximeter as the future of pulse oximeters. Taking advantage of
reflectance oximetry and market shift away from a pulse oximeter on the finger gives PODS a unique
place in the market which it hopes to translate into a successful business. The project is feasible as
demonstrated by the successful preliminary testing of the components and supporting research. There are
still problems to overcome, specifically getting the ADC to work correctly, however this should not stand
in the way of the completion and presentation of a working unit. The PODS product will keep pilots safer
and help to mitigate risk of hypoxia associated with flying at high altitudes in an unpressurized cabin.
30
10 Acknowledgements
Professor Mark Michmerhuizen
Professor Michmerhuizen is the main advisor for team 12.
Class Advisors
Professor David Wunder, Professor Ned Nielson and Professor Jeremy VanAntwerp all assisted the
team through their lectures.
Industrial Consultant
Eric Walstra provided sound guidance and strategies for approaching the different aspects of this project.
31
11 References
n.d. "A Look at the Basics of Bluetooth Technology." Basics | Bluetooth Technology Website. Accessed
November 7, 2014.
n.d. "IEEE 802.11 Standards Tutorial." IEEE 802.11 Standards.
n.d. Mouser. www.mouser.com.
Newegg. n.d. Raspberry Pi B+ Broadcom.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813142003&nm_mc=KNCGoogleAdwords-PC&cm_mmc=KNC-GoogleAdwords-PC-_-pla-_-Embedded+Solutions-_N82E16813142003&gclid=CNbm08us7sECFc1_MgodhnEAWg.
n.d. "Oximetry." Health Library, John Hopkins Medicine.
n.d. "Oximetry." Health Library. John Hopkins Medicine.
2014. Pilot certification in the United States. May 11. Accessed October 9, 2014.
http://en.wikipedia.org/wiki/Pilot_certification_in_the_United_States.
2014. Pulse Oximeter Market Expected to Grow to over $1.3 Billion by 2020 in the U.S., Asia Pacific,
and Europe Combined. September 15. Accessed October 2014. http://globenewswire.com/newsrelease/2014/09/15/666015/10098590/en/Pulse-Oximeter-Market-Expected-to-Grow-to-over-1-3Billion-by-2020-in-the-U-S-Asia-Pacific-and-Europe-Combined.html.
Wax, David B., Philip Rubin, and Steven Neustein. 2009. "A Comparison of Transmittance and
Reflectance Pulse Oximetry During Vascular Surgery." Anesthesia & Analgesia 109.6 1847-849.
n.d. "ZigBee Technology." ZigBee Alliance.
32
12 Appendix 1: Maxim MAX1416 Data Sheet
33
Table 9. Income Sheet
PODS
Pro-Forma Statement of Income
Year 1
Year 2
Year 3
Sales revenue
2,500,000
3,000,000
3,600,000
Variable Cost of Goods Sold
1,000,000
1,200,000
1,400,000
169,750
169,750
169,750
71,450
129,595
102,553
1,258,800
1,500,655
1,927,697
Variable Operating Costs
110,000
130,000
155,000
Fixed Operating Costs
616,250
256,000
256,000
Operating Income
532,550
1,114,655
1,516,697
Fixed Cost of Goods Sold
Depreciation
Gross M argin
Interest Expense
92,250
166,050
129,150
Income Before Tax
440,300
948,605
1,387,547
Income tax (40%)
176,120
379,442
555,019
Net Income After Tax
264,180
569,163
832,528
Table 10. Statement of Cash Flow
PODS
Pro-Forma Statement of Cash Flows
Year 1
Year 2
Year 3
-
1,730,630
2,010,388
264,180
569,163
832,528
Depreciation expense
71,450
129,595
102,553
Invested Capital (Equity)
50,000
-
-
Increase (decrease) in borrowed funds
1,845,000
(369,000)
(369,000)
Equipment Purchases
(500,000)
(50,000)
(20,000)
Ending Cash Balance
1,730,630
Beginning Cash Balance
Net Income After Tax
2,010,388
2,556,469
34
Table 11. Break Even Analysis
PODS
Break - Even Analysis
Year 1
Sales revenue
Year 2
2,500,000
Year 3
3,000,000
3,600,000
Less: Variable Costs:
Variable Cost of Goods Sold
1,000,000
1,200,000
1,400,000
Variable Operating Costs
110,000
130,000
155,000
Total Variable Costs
Contribution Margin
1,110,000
1,330,000
1,555,000
1,390,000
1,670,000
2,045,000
Less: Fixed Costs
Fixed Cost of Goods Sold
169,750
169,750
169,750
Fixed Operating Costs
616,250
256,000
256,000
Depreciation
71,450
129,595
102,553
Interest Expense
92,250
166,050
129,150
Total Fixed Costs
Income Before Tax
949,700
721,395
657,453
440,300
948,605
1,387,547
36
Table 12. Ratio Analysis
Year 1
Total Fixed Costs
Contribution M argin %
Break Even Sales Volume
Break Even Sales Unit Volume
Year 2
Year 3
949,700
721,395
657,453
56%
56%
57%
1,708,094
1,295,919
1,157,374
3,416.19
2,591.84
2,314.75
Equipment
Depreciation
Purchases
Equipment Purchases Year 1
500,000
Equipment Purchases Year 2
50,000
Equipment Purchases Year 3
20,000
M ACRS Rates (7-year recovery period)
Year 1
Year 2
71,450
Year 3
122,450
87,450
7,145
12,245
2,858
0.1429
71,450
129,595
0.2449
0.1749
102,553
Interest Expense:
Annual interest rate on debt
10%
Year 1
Average debt balance
Interest expense
Year 2
Year 3
922,500
1,660,500
1,291,500
92,250
166,050
129,150
Ratio Analysis
Year 1
Year 2
Year 3
Gross M argin of Revenue
Profit M argin
0.76
0.11
0.19
0.23
Net Asset Turnover
2.89
1.60
1.58
Debt to Equity Ratio
37
0.59
0.63
0.55
1.19
37