Anthropomorphic model rigid loading indenter with embedded sensor development for wheelchair cushion standard testing.

Develop an anthropomorphic model cushion rigid loading indenter with embedded sensors (AMCRLI-ES) to assess compression and shear forces at key locations such as trochanters and ischial tuberosities. The sensor design was optimized using finite element analysis. The AMCRLI-ES was designed with the same dimensions as specified in ISO 16840-2 tests. The AMCRLI-ES is divided into eight independent sections, and each section consists of one 3-axis load cell sensor to measure compression and shear forces normal to the compression direction. Six commercial cushions were tested using the AMCRLI-ES with standard ISO 16840-2 testing procedures. Statistical differences were found for energy dissipation between cushions. Statistical differences (p < 0.001) were found in all stiffness values. Test results showed that energy dissipation (ED) was correlated with hysteresis at 500 N with moderate to high Pearson product correlation r = -0.537, p = 0.022. The hysteresis at 250 N did not show a statistical correlation with ED. The AMCRLI-ES demonstrated the ability to measure compression and shear forces at key locations on the cushion including the thigh, trochanter, ischial tuberosity, and sacral area. It provides in-depth information about how the weight was distributed on the cushions.

Design and operation verification of an automated pressure mapping and modulating seat cushion for pressure ulcer prevention.

A sensorized air cell-based seat cushion system was developed to address the issues of loading magnitude and duration at a sitting interface to aid in reducing risk of sitting acquired pressure ulcers. This system is capable of pressure mapping, redistribution, and offloading which were verified using an anthropomorphic model and a human subject. The system is comprised of an air cell array cushion, a pneumatic control unit, and a graphical user interface. ISO load deflection testing confirmed that the cushion's loading response is comparable to commercial air cell-based seat cushions. Testing demonstrated that the internal pressure of the air cells are indicative of interface pressure and can be used as input to pressure modulating algorithms. Uniform pressure distribution was achieved through automated pressure redistribution algorithm implementation where the immersion of a subject into the seat cushion increased and interface pressure decreased. High pressure point identification and automatic offloading were performed in which newly created high pressure points were addressed using subsequent redistribution. Pressure mapping enabled offloading and redistribution can objectively manage the effects of loading magnitude and duration at the sitting interface.