3D Printing as an Adaptive Tool for Sensor Fabrication Applied through pH Monitoring

As a key parameter, pH has received a lot of attention from the sensing perspective. New materials and technologies are being used to produce state of the art devices capable of tracking it. However, most generic sensors lack the applicability that certain applications require. In this article, 3D printing technology is used to its full potential to produce electrodes, which are modified into pH sensors and reference electrodes, with shapre‐driven additional functionality for monitoring ammonia recovery in a bioreactor. The 3D‐printed electrodes are modified with a layer of iridium oxide to be turned into pH sensitive devices. Their characterization showed their characteristic super‐Nernstian response (−77 ± 0.2 mV pH −1 ), high reproducibility (RSD < 5%) between sensors and repeatability (RSD < 2%) between measurements. Moreover, the sensors are stable for at least 20 days and tunable in length. All of this results in the sensors being built into a functional shape and tested to monitor the performance of an ammonia‐producing bioelectrochemical reactor.