1. Under Pressure: Pressure Ulcer Reducing Device
LTU Biomedical engineers – Robert Karas & Corina Malone
UDM Mechanical Engineers– Frank McClosky, Jacob Dodman, & Bobby Lorenz
UDM Nurses – Lydia Jacob, Christina Osterhout, & Victoria Murad
Advisor: Dr. Gerald LeCarpentier

2. Client Background Patient: Mr. Russel Stewart
Trauma caused a spinal cord injury
Developed into a bilateral leg amputee
Suffers from a pressure ulcer
Needs assistance from a caregiver
The Detroit News: Veteran Russel Stewart

3. Disease State Background
2.5 million patients are treated every year for pressure ulcers
25% of patients who suffer from a spinal cord injury develop pressure ulcers
The main risk factors that contribute to pressure ulcer development are pressure distribution, friction, and moisture
Stage 1
Stage 2
Skin Layers
Subcutaneous
Soft Tissues
Bone
Stage 3
Stage 4
Progression of Pressure Ulcer Formation

4. Market Analysis
Stage 1-3 pressure ulcers are treatable by therapeutic device
Stage 4 pressure ulcers require surgery
Average cost to treat a pressure ulcer is $43,180
Insurance companies will cover most of the cost of a wheelchair pad
Most plans are on a 80/20 coverage

5. Predicate Devices Pressure Alternating Pressure Reducing Powered Tilt
Main limitations:
Cost
Independence of patient
Patient Compliance

6. Project Goal
To create a wheelchair pad that incorporates as many features as the predicate devices to allow the patient to be independent and get the maximum therapeutic aid. This prototype device will eliminate the main factors of pressure ulcer formation.
Pressure distribution
Moisture control
Low friction
Bulk weight movement

7. Design Improvements Automatic Comfortable Easy to Clean
Friction Reducing
Portable
Remote Control Operation
Sensor Feedback
Support Standard Weight (300 pounds)

8. Project Development/Improvements
Design Concept – Projects 1
Design for Prototype 1
Final Design

9. Final Design Concept- Projects 2
Key Design Features
8 inflatable bladders
8 force sensors
Timed & Remote control of pattern
Water wicking material
Low friction material
Housing Box to attach circuitry to chair
Inflated Pressure Alternation
Inflated Tilt Phase

10. Design Components Layers of the seat: Gore-Tex outer material
Top foam layer
Force sensors
Inflatable bladders
Bottom foam layer for cushion
Deflated Dimensions (15” x 17” x 1”)
Inflated Dimensions (15” x 17” x 4”)

11. Inflatable Bladder Fabrication
Double layer of plastic sheeting
Cardboard & oven liner
Clothes Iron
Flexible hose
Super glue & electrical tape
Deflated dimensions (8.5” x 4.5” x 0”)
Inflated dimensions (8.5” x 3.75” x 3.5”)
Set-up for bladder fabrication

12. Inflatable Bladder Testing
MTS testing to find burst pressure – 13.6 psi
Bicycle pump test to compare burst pressure – 17 psi
Weight Capacity test – 375 pounds
MTS Testing Fixtures

13. Gore-Tex Material Testing
Waterproof testing to ensure device is easy to clean and the circuitry would survive soiling
Puncture Testing to ensure bladders were safe from sharp objects (keys, pencils, other common items held in pocket)
Resistant Outer Shell
Protective Layer
Gore-Tex Membrane
Protective Layer
Soft Inner Liner
Cross Sectional View of Top Layer

14. Sensor Calibration Weights used ranged from 1-75 pounds
Compared to known weights over area of sensor
Weights used ranged from 1-75 pounds
Linear fit was used on sensor data
Calibration was done by coding on Arduino
Flexi-force Sensor
Calibrating Weights

15. Circuit Design to Control
Designed transistor circuit to allow for control over the pump and individual valves
Uses 4 main components
Transistor
Resistor
Diode
Capacitor
Circuit Design to Control
Pump and Valve
Circuit Prototype

16. Seat Fabrication Sensors adhered to bladder
Bladders sewn to top foam layer
Hoses run through bottom foam layer
Foam layers adhered together
Outer material sewn together
Set-up for Seat Fabrication

17. Prototype Testing Air splitter achieved even inflation of bladders
Remote control worked after extended use
Cycle continued after extended use
Device could withstand water
Hoses could not be felt when seated
High force caused change in sequence
Student Testing Device Capabilities

18. Usability Testing Remote could work at different angles
Tilt angle of 15 degrees was comfortable and safe
Resistant to hoses coming disconnected
Weather/soiling resistant
Comfort after an extended period of time
Client Testing Device Prototype

19. Safety Risk

20. Final Budget
Final product could sell from $600-$1000 due to high cost of existing pressure relieving devices

21. Final Timeline COMPLETED TASK REPSONSIBILITY START DATE
EXPANDED
REPSONSIBILITY
START DATE
COMPLETION DATE
BLADDER FABRICATION
FABRICATE SEVERAL BLADDERS FOR DEVICE AND TESTING
ROB
FEB 22
APRIL 13
ARDUINO CODING
CODING FOR VALVES, PUMP, SEQUENCING, POWER, SENSORS
UDM ENGINEERS
APRIL 1 3
CIRCUIT ASSEMBLY
FOR ACTIVATING PUMP AND VALVES
MAR 23
COMPONENT TESTING
TO DETERMINE SAFETY AND FUNCTIONALITY OF INDIVIDUAL PARTS
ROB & CORINA
MAR 26
MAR 31
SEAT ASSEMBLY
ALL COMPONENTS PUT TOGETHER SECURELY AND EFFECTIVELY
CORINA
MAR 1
APRIL 20
PROTOTYPE 1
ENSURE ALL DEIVCE COMPONETS WORKED TOGETHER TO ACHIEVE EXPECTED DELIVERABLES
ALL TEAM MEMBERS
MAR 16
SENSOR CALIBRATION
CALIBRATION OF SENSORS TO ENSURE UNIFORM READINGS AND FUNCTIONALITY
APRIL 11
APRIL 17
DEVICE TESTING
BURST PRESSURE, MAX LOAD, PUNCTURE TEST,
APRIL 15
APRIL 19

22. Pressure Ulcer Reducing Pad : Under Pressure Pad
Robert Karas & Corina Malone
Dr. Gerald LeCarpentier
Objective: Create a device that can be used as a chair cushion to prevent pressure ulcer formation, and provide the patient with a solution that allows them to operate the device independently.
Approach: Use inflating bladders to help redistribute pressure and tilt the patient 15 degrees in order to help blood circulation and oxygen levels in the injury site to improve. Also, use force sensors in order to prevent any dangerous amount of pressure on any one point.
Impact: Keep patients out of the hospital by using this wheelchair pad that is comfortable, independent, and properly manages the risk factors associated with pressure ulcers.
Progress and Results:
8 air bladders fabricated to withstand 375 pounds
Calibration and implementation of force sensors
Arduino code that operates automatically and has overrides for sensor data or user input
15 degree of tilt achieved by inflatable bladders
Outer material can withstand puncture and water
Pressure Alternating
Tilt Phase
Veterans Testing Prototype
Bladder Testing Data