Printed potentiometric sensors

From environmental monitoring, industrial process control, to point-of-care biofluid analysis, ion sensing has always been a pivotal topic. As the most suitable tool for ion sensing, potentiometric ion sensors are routinely used in these areas. Today, over a billion measurements with potentiometric sensors are preformed globally and hundreds of companies sell ready to use blood-gas analyzers with potentiometric sensors. Tremendous advances over the past decades in the printing technology have opened a new paradigm for low-cost, large-scale and robust fabrication of a new generation of future potentiometric ion sensors for wearable devices and electronic skin. Unfortunately, up to now, the fully printed potentiometric ion sensor has not yet been truly realized. Hence, it is highly desired to address the sensor fabrication challenges, and further extend application scenarios of potentiometric ion sensors. Herein, up-to-date potentiometric sensors fabricated via the printing technology including 2D and 3D printing are highlighted. The application scenarios of these printed sensor are also discussed. Furthermore, the existing challenges and future prospects are provided. We hope that this review will shed new lights on the understanding of printed potentiometric sensors and pave the way for the widespread applications of these chemical sensors.