Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Chemical and Biological Engineering

First Advisor

Patrick E. Patterson


Little is known about the dynamic pressure distribution changes, as compared to static pressure distribution, that take place on the sitting surface of a wheelchair while one propels oneself on a level surface. An understanding of these dynamic pressures may influence the design of wheelchair seat cushions designed to minimize pressure sores. This research investigates dynamic interfacial pressure changes on the seated wheelchair user during short bursts of locomotion on a level surface;Ten nondisabled subjects sat in a sling-seat wheelchair while eleven disabled subjects used their own sling-seat wheelchairs without a cushion. Only those capable of manually propelling themselves were considered;Pneumatic bladders arranged in a flexible grid matrix (50 elements covering a 7.5" x 15" area) were instrumented with miniature piezoresistive pressure transducers and placed between the user and the wheelchair seat. One half of the subject/seat interface was instrumented. The other half was covered with one-half-inch-thick foam. Dynamic pressure distributions in the left and right halves were measured in separate trials for every subject. Each sensor was sampled at 10 Hz during the time it took the subject to traverse 25 feet from start to stop;Disability level (disabled or nondisabled), morphology (fat, thin, or muscular) and locomotion period (acceleration, coast, or deceleration) were examined for their effect on maximum pressure (magnitude and location), average pressure (magnitude and location), area above 35 mmHg (magnitude and location) and maximum deviation in the center-of-pressure. Data was with respect to static conditions. Side effect (left, right) was accounted for prior to the independent variable effects;There were effects due to disability on the smallest global average pressure, largest threshold area and largest global maximum (p ≤ 0.05). There were no morphology effects. Period of locomotion had an effect on all variables except location of largest global average, location of largest global maximum, and location of largest threshold area (p ≤ 0.001). Two-tailed t-tests of the relative dependent variables revealed that all 13 dependent variables varied with respect to the static conditions (p ≤ 0.0001) indicating a dynamic nature.



Digital Repository @ Iowa State University,

Copyright Owner

Karl Matthew Eckrich



Proquest ID


File Format


File Size

171 pages