Development of a pH based tissue ischemia monitor: hardware realization

The objective of the authors' research is to develop a pH measuring system which will be used for accurate postoperative monitoring of transplanted tissue. Currently, most pH monitors that are used for this purpose are difficult to operate for hospital personnel and do not possess sufficient long-term stability, resulting in false readings of tissue pH. To resolve these problems, an electronic multichannel pH measuring device, that interfaces with a laptop computer, was constructed. The system makes use of an algorithm to compensate for instabilities that are inherent to pH measurements. This is accomplished using separate pH reference electrode channels from which multiple measurements are taken and averaged. Preliminary tests show that this system accurately measures pH and remains stable during 96 hour test periods.