A microprocessor-based tissue displacement monitor for in vitro quantification of knee capsule deformation.

The advantages of utilizing a microprocessor design kit as a central element in custom laboratory instrumentation are demonstrated in the design of a real-time, multiple point, tissue displacement monitor. The tissue sample to be monitored is submerged in a saline bath, through which perpendicular electric fields are alternately generated. Analog displacement data are generated by differentially amplifying the voltage between each of 4 sense electrodes attached to the tissue surface, and a reference electrode, positioned on the tissue surface central to the sense electrodes. The microprocessor unit is used to control field generation, to multiplex the sensing electrode signals through the analog signal processing electronics, and after analog-to-digital conversion, to scale and interface the digital displacement data to a host processor.