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 1 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. 2 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 ......................................... 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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 6 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 7 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. 8 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 7 10 13 18 21 22 23 24 25 26 28 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. 9 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 10 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. 11 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. 12 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. 13 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.) 14 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) 15 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