Wearable Dual-Signal NH Sensor with High Sensitivity for Non-invasive Diagnosis of Chronic Kidney Disease.

NH gas in human exhaled breath contains abundant physiological information related to human health, especially chronic kidney disease (CKD). Unfortunately, up to now, most wearable NH sensors show inevitable defects (low sensitivity, easy to be interfered by the environment, etc.), which may lead to misdiagnosis of CKD. To solve the above dilemma, a nanoporous, heterogeneous, and dual-signal (optical and electrical) wearable NH sensor mask is developed successfully. More specifically, a polyacrylonitrile/bromocresol green (PAN/BCG) nanofiber film as a visual NH sensor and a polyacrylonitrile/polyaniline/reduced graphene oxide (PAN/PANI/rGO) nanofiber film as a resistive NH sensor are constructed. Due to the high specific surface area and abundant NH binding sites of these two nanofiber films, they exhibit good NH sensing performance. However, although the visual NH sensor (PAN/BCG nanofiber film) is simple without the need of any detecting facilities and quite stable when temperature and humidity change, it shows poor sensitivity and resolution. In comparison, the resistive NH sensor (PAN/PANI/rGO nanofiber film) is of high sensitivity, fast response, and good resolution, but its electrical signal is easily interfered by the external environment (such as humidity, temperature, etc.). Considering that the sensing principles between a visual NH sensor and resistive NH sensor are significantly different, a wearable dual-signal NH sensor containing both a visual NH sensor and resistive NH sensor is further explored. Our data prove that the two sensing signals in this dual-signal NH sensor mask can not only work well without interference with each other but also complement each other to improve the sensing accuracy, indicating its potential application in non-invasive diagnosis of CKD.