Development of an impedance spectrometer for tissue ischemia monitoring: application of synchronous sampling principle

The objective of our research Is to develop an impedance spectrometer which will be used for tissue ischemia monitoring. After analyzing the standard methods for complex impedance measurements, a new system realization was proposed. The approach is based on the four electrode impedance measurement method, using synchronous sampling demodulation with one analog channel. Realization of this method, based on the newest generation of highly integrated electronic components for generating sinusoidal signals of arbitrary frequencies, is simple and provides accurate measurements. This approach enables complete microprocessor control of measurements. It has the potential to be fully integrated into a hand-held instrument.