incubator designed for emerging areas ( ideagartnerm/08/incubator/thefinalseniordesign... ·...

Incubator Designed for Emerging Areas (iDEA)

University of PittsburghSenior Design – BioE 1160-1161

Areas (iDEA)

Ted Kastenhuber

Bradley H. Morneweck

Bailey M. Roche

Christopher E. Withers

Outline

• Overview• Project Objectives• Features & Benefits• Competitive Analysis• Quality System Considerations• 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 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, low-maintenance neonatal incubator relevant to hospital situationhospital situation

• Projected intended to be a simple re-design of well-established incubation methods

Infantmortality:73 of 1,000

http://www.hashaiti.org/

Outline




Project Objectives

• Design functioning neonatal incubator

• Must be under $500

• Temporarily/semi-permanently operable outside of a variety of power gridsoutside 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




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 operationis 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




Competitive Analysis

• Modern Incubators (Dräger Medical)

• Extremely complex• Very expensive• Very expensive• Require extensive

maintenance by highly-trained technicians

http://www.gehealthcare.com/usen/perinatal/micro_environments/giraffe/images/giraffe_ph_prod_l.jpg

Competitive Analysis• HEBI

+ Cheap (€325 ~$510)+ Easy to use- Difficult to set up- No fine temperature control

• Kangaroo Mother Care (KMC)+ Cheap (free)

http://www.hebi-incubator.orghttp://www-conference.slu.se/KMCeurope08/bilder/Ylvasfoto5.jpg

Prasanga et. al., 2002

+ 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 HEBI KMC PCPI iDEA

Cheap

User Friendly

Meets Modern Standards

Requires LessRequires LessNurse Attention

Safe

Baby Accessible for Procedures

Outline




Quality System Considerations

• Risk analysis• Significant risks

• Electrical failure causing fire• Loss of 1o C heat precision• Air infection• Loss of airflow• 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 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




Our Design

• Adequate Warmth

• Adequate Humidity

• Infant Visibility• Infant Visibility

• Infant Accessibility

• Air Filtration

• Sterility Maintenance

Our Design

Thermoregulation Unit

12V Battery (Thermoregulation

unit dedicated)

Surgical Mask Filtration

Access Ports

Humidity Chamber

Temperature Chart1

12V Battery

1. Kloesz, Jennifer L. Personal interview. 6 Oct. 2007.

Humidity Chamber and Power Supply

Housing

Bassinet

Access and Visibility

• Access Ports

• Sliding platform

• Transparent faces• Transparent faces

PowerAC DC

ePOWER EP-520XP-C1B ATX12V 520W Power Supply (x2)

Autocraft 12V Marine/RV Deep Cycle battery

(Supplied by HAS)

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 intakeActive outtake, passive intake

Cost Analysis

Material Cost (USD)

Wood 75

Plexiglass 40

Hardware 50

Power supplies 70

PC fans 10PC 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

iDEA

HEBI

Dräger1. Kloesz, Jennifer L. Personal interview. 6 Oct. 2007.

User input

• Set point temperature

• On/off

• Battery or AC power• Battery or AC power

• Alarm circuit on/off

Outline




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

60.00%

65.00%

70.00%

75.00%

80.00%

Rel

ativ

e H

um

idit

y (%

)Relative Humidity over Time

Red Squares -- starting water temp = 52 deg C

Blue Diamonds -- starting water temp = 30 deg C

Green Triangles -- included water heater

30.00%

35.00%

40.00%

45.00%

50.00%

55.00%

0 10 20 30 40 50 60

Rel

ativ

e H

um

idit

y (%

)

Time (min)

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• Positive control outside

• Swabbed• Inside bassinet

• Inside humidity bay

• Inside water pan

Sterilityt0 = right after cleaning with ethanol

+ Control

Humidity Bay

Water Pan

Bassinet

tF = after 5 hours of running incubator

BassinetWater Pan

Humidity Bay

+ Control

Clinician Feedback

• Initial Impressions• Received well by Dr. Mahmood, Magee-

Women’s Hospital

• “I could see this device in my part of the • “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 5

Responsiveness 1 2 3 4 5

Mechanical Operability 1 2 3 4 5

4.67

3.67

4.67

Ergonomic and Aesthetic Quality 1 2 3 4 5

Three participants of backgrounds:1. MD, Neonatologist fellow2. High school equivalent3. B.S., Bioengineering

4.33

Project ManagementDec Jan Feb Mar Apr

3D Design

Heating/Humidityelement design

Alarm Circuitry

Device assembly

Verification/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 • 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• 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

• Ian Rawson, MD• Burhan Mahmood, MD • Jack Patzer, PhD• Rich Stoner• Andy Alexander• 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

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

Function or Component

Failure Mode Effect on System Possible HazardsRisk

IndexUser 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

10Monitoring 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 failsInfant remains in an over or under-heated state for an amount of time that is fatal

10Monitoring 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 functionAlarm 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

15Monitoring of system shows temperature reads too high or low and no alarm has sounded

Provide instructions for replacement; recommend regular tests

Table & legsFailure 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 openInfant 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 OcclusionAir ceases to be able to pass through device

Oxygen depletion, asphyxiation of infant

12Visual 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

FanMechanical failure, circuit failure

Air ceases to be pushed through device

Overheating of infant, oxygen depletion, asphyxiation

14 Visual or auditory recognition of fan failureEnsure fan component is easily replaceable, provide warnings for use

Heating lamps/bulbsBurnout, improper connection

Air ceases to be heatedHypothermia; shock, burns, broken glass hazards

9 Visual recognition or alarm sounds.

Use low wattage light bulbs; suggest having readily available back-up; use shatter-proof spotlight.

Redesigns• Bassinet

• Plexiglas vs. wood

• Added features

• Humidifier• 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

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