A compound sensor for biomechanical analyses of buttock soft tissue in vivo.

A sensor for in vivo biomechanical characterization of buttock soft tissue has been developed and evaluated. The sensor measures interface pressure, applied force, tilt, and rotation angle of the sensor head, and the thicknesses of multiple soft tissue layers. A composite ultrasonic transducer using a 1-3 ceramic-polymer structure was developed for the sensor. The sensor can identify subcutaneous soft tissue interfaces 5 to 65 mm below the skin surface with a 0.26-mm axial resolution, pressure over the range of 0 to 68 kPa, and force over the range of 0 to 3.6 kg. Our purpose for developing the sensor was to study the biomechanical characteristics of buttock soft tissues. Successful identification of distinguishing characteristics in persons with a susceptibility to pressure ulcers may result in the development of a risk assessment tool based on tissue characterization.