Multifunctional Dopamine‐Based Hydrogel Microneedle Electrode for Continuous Ketone Sensing

Abstract Diabetic ketoacidosis (DKA), a severe complication of type 1 diabetes (T1D), is triggered by production of large quantities of ketone bodies, requiring patients with T1D to constantly monitor their ketone levels. Here, a skin‐compatible hydrogel microneedle (HMN)‐continuous ketone monitoring (HMN‐CKM) device is reported. The sensing mechanism relies on the catechol–quinone chemistry inherent to the dopamine (DA) molecules that are covalently linked to the polymer structure of the HMN patch. The DA serves the dual‐purpose of acting as a redox mediator for measuring the byproduct of oxidation of 3‐beta‐hydroxybutyrate (β‐HB), the primary ketone bodies; while, also facilitating the formation of a crosslinked HMN patch. A universal approach involving pre‐oxidation and detection of the generated catechol compounds is introduced to correlate the sensor response to the β‐HB concentrations. It is further shown that real‐time tracking of a decrease in ketone levels of T1D rat model is possible using the HMN‐CKM device, in conjunction with a data‐driven machine learning model that considers potential time delays.