21.2 A $\boldsymbol{22\mu \mathrm{W}}$ Peak Power Multimodal Electrochemical Sensor Interface IC for Bioreactor Monitoring

Bioreactors are employed in many industries like food, beverage, chemical, and biopharmaceutical to grow biologically active compounds. Bioreactors range in size from large industrial tanks for manufacturing to small single-use vessels for process flow development or research purposes like vaccine discovery. To ensure optimal bioreactor operation, there is a need to monitor various parameters, including temperature, acidity, oxidation-reduction potential (ORP), dissolved oxygen, ion concentrations, and other metabolites like glucose and lactate. Usually, these are measured with glass probes and tubes fed into the bioreactor via holes in the lid or side, resulting in bulky and complex systems. An attractive alternative solution is a small wireless monitoring device floating inside or attached to the wall, as shown in Fig. 21.2.1 (left). Since the sensors are specific to the process to be monitored and degrade over time, the sensors preferably are replaceable while the electronics could be reusable. Electrochemical sensing with ion-selective electrodes (ISEs) and ion-selective FETs (ISFETs) is attractive for small form factor, low-power sensors [1]–[4], but it requires specialized readout electronics to achieve the vision outlined in Fig. 21.2.1. In this paper, we present a low-power electrochemical sensor interface IC with support for common electrochemical sensing principles (ISFET, amperometric, and potentiometric) for in-situ bioreactor monitoring.