Performance Analysis of a Flexible HPTS-Based Carbon Dioxide Sensor for Transcutaneous Blood Gas Monitoring

Traditional transcutaneous carbon dioxide sensing methods often require frequent calibration and the replacement of measurement electrodes, often deployed in large devices. In our pursuit of developing an accurate and noninvasive method for transcutaneous carbon dioxide sensing, we have introduced the utilization of a carbon dioxide-sensitive flexible sensor patch consisted of 8-hydroxypyrene-1,3,6-trisulfonate. To assess its performance, we have designed custom circuitry and conducted various tests to evaluate the sensor’s reactivity to changes in the partial pressure of carbon dioxide, as well as its response to external parameters, such as excitation intensity, measurement drift, humidity, and temperature. Through our testing, we implemented a ratiometric approach and discovered that the sensor exhibits a linear relationship between the luminescence ratio and changes in carbon dioxide partial pressure. Within the clinically relevant range, we successfully measured carbon dioxide partial pressure, showing a variation of less than 3.9% across different levels of excitation intensity.