Material test was performed in compression and tension on swine, lamb, and human tissues with different experimental setups.
Three experimental setups were used: A custom made Micro Testing Machine “MTM” with ±2mN load resolution and ±1mm stroke capacity, The ELF-3100, Testing Instrument with ±22N and ±2.5mm ranges, and a 100L Dynamic Material Testing Machine with ±50N and ±25mm ranges.   
Experimental setup for ex vivo soft tissue compression test.
Compression mechanism 3 (Pre-stretched) 
Figure. Stress-strain results for muscle, fat, skin and fascia from tensile and compression material test.
Fitting hyperelastic material models to the experimental data: The strain energy potentials were fitted to the experimental data. The material was assumed as incompressible. The tested material models included: Arruda-Boyce, Marlow, Van Der Waals, Reduced Polynomial (N=1: Neo-Hooken, 2, and 3: Yeoh), Polynomial (N=1: Mooney Rivilin, and 2), Ogden (N=1, and 3) Findings: Generally, material behaviors for skin and fat were favorably represented by the fitted strain energy potentials. However, material behavior for muscle was relatively less represented by the strain energy potential. It was found that for the tested soft tissues, the Polynomial (N= 2) and Ogden (N=1) gave the best fitted results with R2 higher than 0.99. However, since the fitting results were for limited amount of tissue samples, the selection of material models for the proposed study should not be limited to these 2 options. To investigate material properties in buttock tissues in chronic SCI patients using a Tissue Ultrasound Palpation System (TUPS) (Collaboration with Hong Kong Polytechnic University)
It is hypothesized that chronic SCI may affect material properties of soft tissue below the injury level. This property alteration may contribute to soft tissue breakdown in wheelchair users with chronic SCI. TUPS is a portable solution to measure soft tissue mechanical properties in vivo. In this project, measurement is performed on people with and without chronic SCI to identify possible difference in their buttock tissue material properties. 
| 
