Scalable Manufacturing of Radiation‐Tolerant Potentiometric Electrodes: A Systematic Transition from Laboratory to Semiautomated Fabrication

A “lab‐to‐fab” transition is described that enables the semiautomated production of thin‐film potentiometric pH electrodes, designed for use in sterile single‐use bioreactors. Manual methods of materials deposition and film casting are replaced with spray coating on a moving web and the production of membranes with a programmable dispenser operating at constant rates. These provide a greater degree of control over membrane thickness and a reduction in voltage spread between electrodes, which are evaluated in batches using a multichannel analyzer. γ‐ray ionization of the pH electrodes introduces a predictable voltage drift that follows a log decay function on the day timescale; the voltage decay rate correlates with membrane thickness and can be modeled as a parallel diode–capacitor circuit. Batches of radiation‐sterilized pH electrodes are tested in cell culture media and yield mean pH values within 0.05 units relative to a commercial meter (ground truth) following a single‐point calibration protocol. Quantitative uncertainty analysis attributes more than half of total error to variations caused by ionizing radiation and yields novel insights into strategies for reducing uncertainty.