Single bi-functional flexible sensor device for simultaneous pH and oxygen monitoring during pre-transplant normothermic perfusion

Monitoring of organ health and tissue damage through real-time sensing of chemical parameters such as pH and oxygen concentration could provide helpful information in the field of solid organ transplantation. Several sensors have been developed to detect oxygen concentrations and pH levels in tissues separately; however, there is no report to date on a single device in such context that can detect both pH and oxygen alterations simultaneously and in real time. This paper reports the development of a single, bi-functional optical sensor device that can simultaneously and reversibly respond to changes in both pH and oxygen concentration. The proposed optical sensor integrates both pH- and oxygen-sensitive probes, and is optimized to achieve minimal cross-sensitivity during simultaneous measurements. The sensor is excited with light of 405 nm wavelength to detect pH and oxygen changes respectively at emission wavelengths of 520 nm and 600 nm. The sensor detects pH and oxygen alterations with a response time of about 12.5 s and less than 1.5 s, respectively. The sensor exhibits a sensitivity of 75.75% for pH variations and 20.4% per mg/ml for changes in oxygen concentration. The sensor was tested on a human liver declined for transplantation to analyse the initial sensor behaviour on human tissue. Including the sensor in an organ perfusion setup to monitor pH and oxygen levels could potentially provide insight into the microcirculation of an organ before transplantation.