University of Pittsburgh
Senior Design – BioE 1160-1161
Incubator Designed for Emerging
Areas (iDEA)
Ted Kastenhuber
Bradley H. Morneweck
Bailey M. Roche
Christopher E. Withers
Outline
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Overview
Project Objectives
Features & Benefits
Competitive Analysis
Quality System Considerations
Regulatory Considerations
Our Design
• Considerations
• Development
• Verification & Validation
Overview
• Infant Mortality in Developing Countries
• 98% of reported neonatal deaths occur in
the developing world
• One of the leading causes is failure to keep
babies warm, which leads to increased
hypothermia, decreased metabolism and
infection
Zupan, Jelka “Perinatal Mortality in Developing Countries”, N ENGL J MED
352;20. 2005. 2047-2048
Overview
• Project contact: Dr. Ian Rawson, Hôpital
Albert Schweitzer in Haiti
• Hospital requires a low-cost, lowmaintenance neonatal incubator relevant to
hospital situation
• Projected intended to be a simple re-design
of well-established incubation methods
Infant
mortality:
73 of 1,000
http://www.hashaiti.org/
Outline
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Overview
Project Objectives
Features & Benefits
Competitive Analysis
Quality System Considerations
Regulatory Considerations
Our Design
• Considerations
• Development
• Verification & Validation
Project Objectives
• Design functioning neonatal incubator
• Must be under $500
• Temporarily/semi-permanently operable
outside of a variety of power grids
• Carry out four functions in accordance with
FDA standards
• Thermoregulated heating
• Appropriate humidity maintenance
• Adequate ventilation maintenance
• Maintenance of sterility
Outline
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Overview
Project Objectives
Features & Benefits
Competitive Analysis
Quality System Considerations
Regulatory Considerations
Our Design
• Considerations
• Development
• Verification & Validation
Features & Benefits
• Thermoregulated System with alarm means
that busy clinicians can go about their tasks
assured that infant is safe
• Simple interface ensures that minimal training
is required for operation
• Low cost/accessible parts enable the device
to be maintained on-site
• Compatibility with independent power supply
ensures that device may be operable under
conditions with limited or unreliable power
supply
Outline
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Overview
Project Objectives
Features & Benefits
Competitive Analysis
Quality System Considerations
Regulatory Considerations
Our Design
• Considerations
• Development
• Verification & Validation
Competitive Analysis
• Modern Incubators
(Dräger Medical)
• Extremely complex
• Very expensive
• Require extensive
maintenance by highly-trained
technicians
http://www.gehealthcare.com/usen/perinatal/micro_environments/giraffe/images/giraffe_ph_prod_l.jpg
http://www.hebi-incubator.org
http://www-conference.slu.se/KMCeurope08/bilder/Ylvasfoto5.jpg
Prasanga et. al., 2002
Competitive Analysis
• HEBI
+
+
-
Cheap (€325 ~$510)
Easy to use
Difficult to set up
No fine temperature control
• Kangaroo Mother Care (KMC)
+ Cheap (free)
+ Easy
- Cumbersome
- Possibility of disease transmittal
• Phase Change Passive Incubator (PCPI)
+ Lightweight
- Actual development is very meager
* Senior design project at MIT
Competitive Analysis
Parameter
Cheap
User Friendly
Meets Modern
Standards
Requires Less
Nurse Attention
Safe
Baby Accessible
for Procedures
HEBI
KMC
PCPI
iDEA
Outline
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Overview
Project Objectives
Features & Benefits
Competitive Analysis
Quality System Considerations
Regulatory Considerations
Our Design
• Considerations
• Development
• Verification & Validation
Quality System Considerations
• Risk analysis
• Significant risks
• Electrical failure causing fire
• Loss of 1o C heat precision
• Air infection
• Loss of airflow
• General system responses
• Failsafe systems respond
• Alarm sounds
• Device powers down (sounding alarm)
Regulatory Considerations
• Class II
• FDA regulation 21 CFR 880.5400 – previous
incubators designated class II
• Also regulation: IEC 60601-2-19 1996-10:
Amendment 1 - Medical electrical equipment Part
2: Particular requirements for safety of baby
incubators, which pertains to the 510(k) specifics.
• Third world application, bypasses FDA
Outline
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Overview
Project Objectives
Features & Benefits
Competitive Analysis
Quality System Considerations
Regulatory Considerations
Our Design
• Considerations
• Development
• Verification & Validation
Our Design
• Adequate Warmth
• Adequate Humidity
• Infant Visibility
• Infant Accessibility
• Air Filtration
• Sterility Maintenance
Our Design
Thermoregulation
Unit
Surgical Mask
Filtration
Access Ports
12V Battery
(Thermoregulation
unit dedicated)
Humidity Chamber
and Power Supply
Housing
Temperature Chart1
12V Battery
1. Kloesz, Jennifer L. Personal interview. 6 Oct. 2007.
Bassinet
Access and Visibility
• Access Ports
• Sliding platform
• Transparent faces
Power
AC
DC
Autocraft 12V Marine/RV
Deep Cycle battery
(Supplied by HAS)
ePOWER EP-520XP-C1B ATX12V 520W
Power Supply (x2)
9 V Battery for independent alarm circuit
Heat
Rally 12V Heater (200W)
$5.99
CE PTC Ceramic
Heater & Fan (300W)
$25.00
Circuit
MaxxTronic – MX052 –
Digital Thermoregulator
$39.95
Alarm Circuit1 -- $1.00
1. Stetten, George. "Comparators, Photoresistor,
Thermoregulation, Hysteresis." University of
Pittsburgh. Benedum Hall, Pittsburgh. 6 Apr. 2008
<http://www.stetten.com>.
Humidifier
PC fan
~$7.99 ea.
Oven Pan
$5.00
Ventilation
12V CoolerMaster computer
fan (x2)
Active outtake, passive intake
Cost Analysis
Material
Cost (USD)
Wood
75
Plexiglass
40
Hardware
50
Power supplies
70
PC fans
10
Heaters
31
Maxtronic Thermoregulatory circuit
40
Misc. electronic supplies
70
Caulk, sealant, etc.
20
Bulb Thermometer
31
Water pan
5
Total
442*
*Note: The above prices reflect prototype production. During mass production, unit prices will be markedly lower.
Cost Analysis
$442.00
$510.22
$40,0001
HEBI
iDEA
Dräger
1. Kloesz, Jennifer L. Personal interview. 6 Oct. 2007.
User input
• Set point temperature
• On/off
• Battery or AC power
• Alarm circuit on/off
Outline
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Overview
Project Objectives
Features & Benefits
Competitive Analysis
Quality System Considerations
Regulatory Considerations
Our Design
• Considerations
• Development
• Verification & Validation
Thermoregulation
*Note: Resolution of data logger is 0.5°C.
(set point = 37.0°C)
Thermoregulation
• Initial tests indicate that servo control is
possible
Humidity
Relative Humidity over Time
80.00%
Red Squares -- starting water temp = 52
deg C
75.00%
Relative Humidity (%)
70.00%
Blue Diamonds -- starting water temp =
30 deg C
65.00%
Green Triangles -- included water
heater
60.00%
55.00%
50.00%
45.00%
40.00%
35.00%
30.00%
0
10
20
30
Time (min)
40
50
60
Ventilation
Ethanol Candle Test
14.335 g / 30 minutes
=
232.7 mL O2/min
A baby requires 2.48 mL O2/min*
Oxygen requirements of candle exceed neonate by nearly
100, thus validating ventilation
*Libert JP, Bach V, Farges G. 1997. Neutral temperature range in incubators: performance of equipment in current
use and new developments. Crit Rev Biomed Eng 25(4-5):287-370.
Sterility
• Swabbed for bacterial growth
• Time points: t0 = after ethanol
cleansing; tF = after 5 hour run
• Positive control outside
• Swabbed
• Inside bassinet
• Inside humidity bay
• Inside water pan
Sterility
t0 = right after cleaning with ethanol
+
Control
Humidity
Bay
Water
Pan
Bassinet
tF = after 5 hours of running incubator
+
Control
Humidity
Bay
Water
Pan
Bassinet
Clinician Feedback
• Initial Impressions
• Received well by Dr. Mahmood, MageeWomen’s Hospital
• “I could see this device in my part of the
world being used”
• Survey:
• Scale 1-5:
• Ease of use, Utility, Safety
Survey
Ease of Use
1
2
3
4
Responsiveness
1
2
3
3.67 4
Mechanical Operability
1
2
3
4
Ergonomic and Aesthetic Quality
1
2
3
4
Three participants of backgrounds:
1. MD, Neonatologist fellow
2. High school equivalent
3. B.S., Bioengineering
4.67
5
5
4.67
4.33
5
5
Project Management
Dec
Jan
Feb
Mar
Apr
3D Design
Heating/Humidity
element design
Alarm Circuitry
Device assembly
Verification/
Validation
Send to Haiti
Each group member contributed equally to
each aspect of the design process
Comparison to PDS
• Cost less than $500
• Must regulate temperature at set points
29-35˚ C
• Must alert staff if the temperature falls
out of range
• Patient must be visible in the device
Comparison to PDS
• Noise < 47 dB (via Audacity™)
• Dimensions < (2m x 2m x 2m)
• Access to infant in less than 5s
• Easily portable
• Humidity > 40%
Moving Forward
• Immediate (Through April)
• Come up with production plan
• Long term (Early June?)
• Create final product (kit)
• Send and install device in HAS
Acknowledgements
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Ian Rawson, MD
Burhan Mahmood, MD
Jack Patzer, PhD
Rich Stoner
Andy Alexander
Shawn Burton
Sources of funding
• Generous gift of Drs. Hal Wrigley and Linda Baker
• Department of Bioengineering
• NCIIA BMEidea stipend award
?
Failure Mode Effect Analysis
Function or
Component
Failure Mode
Effect on System
Hazard Risk Index
Acceptance Criteria
1 to 5
Unacceptable
6 to 9
Undesirable
10 to 16
Acceptable upon completion of quality assurance review
17 to20
Acceptable without review
Possible Hazards
Risk
Index
User Detection Means
Applicable Controls
Electrical
thermoregulation unit
Incomplete/short circuit,
thermistor malfunction
Temperature of the
system deviates from set
value
Over or underheating of the
infant, dehydration; shock from
circuit itself
10
Monitoring of temperature shows system is
not being moderated adequately; alarm
sounds
Utilize circuit components with
low voltage demands
Electrical
thermosensitive alarm
unit
Incomplete/short circuit,
thermistor malfunction;
incorrect input to alarm
Alarm fails
Infant remains in an over or
under-heated state for an
amount of time that is fatal
10
Monitoring of system shows temperature
reads too high or low and no alarm has
sounded
Utilize circuit components with
low voltage demands; provide
detailed, clear schematics for repair
Auditory Alarm
Burnout or loss of function
Alarm fails to sound in
the event of large
deviation from set value
Infant remains in an over or
under-heated state for an
amount of time that is fatal
15
Monitoring of system shows temperature
reads too high or low and no alarm has
sounded
Provide instructions for
replacement; recommend regular
tests
Table & legs
Failure to provide adequate
support
Device falls unexpectedly Trauma to infant
12
Visual observation.
Ensure that device platform is
structurally sound, provide
warnings for incubator placement
Box/insulation
component
Insufficient capacity to
retain heat; puncture
Device is unable to reach
set temperature value
Infant temperature too low,
hypothermia
14
Alarm sounds.
Warnings and detailed instructions
for leak repair
Doors and hinges
Unable to easily open
Infant trapped inside of
incubator
Asphyxiation, overheating,
dehydration of infant
17
The door resists opening.
Enable hinges to be manually
detached, provide warnings for
proper handling of doors + hinges;
recommend regular tests
Holes
Occlusion
Air ceases to be able to
pass through device
Oxygen depletion, asphyxiation
of infant
12
Visual inspection of occlusion, unable to
feel air flow placing hand over the hole
Ensure hole diameters are at a
value that minimizes both
occlusion occurrence and heat loss
Fan
Mechanical failure, circuit
failure
Air ceases to be pushed
through device
Overheating of infant, oxygen
depletion, asphyxiation
14
Visual or auditory recognition of fan failure
Heating lamps/bulbs
Burnout, improper
connection
Air ceases to be heated
Hypothermia; shock, burns,
broken glass hazards
9
Visual recognition or alarm sounds.
Ensure fan component is easily
replaceable, provide warnings for
use
Use low wattage light bulbs;
suggest having readily available
back-up; use shatter-proof
spotlight.
Redesigns
• Bassinet
• Plexiglas vs. wood
• Added features
• Humidifier
• Simple
• Capillary action
• Enclosed pan
• Open chamber with forced air
Redesigns
• Thermoregulation circuit
• Op Amp comparator
• PIC controller
• MaxxTronic
• Alarm Circuit
• Data logger
• Op Amp Comparator