Filter, Flip, and Fabricate: A Wax-Assisted Stamp-Transfer Approach for Flexible Ti3C2Tx MXene Electrochemical Transducers

Combining additive-free solution processing of MXenes with template-assisted transfer represents an innovative approach for the fabrication of electrochemical sensors. Herein, we introduce a wax-assisted templating and stamp-transfer (WAST) approach to fabricate monolithic MXene transducers. To this end, two configurations were developed: (A) MXene-at-all electrodes, where the working, counter, and reference electrodes were entirely composed of MXene, and (B) MXene working electrodes combined with an Ag/AgCl pseudoreference and carbon counter electrodes. Additive-free MXene inks, at different concentrations and volumes, were filtered onto wax-templated PVDF membranes to form stampable patterns. Voltammetric characterization revealed consistent anodic and cathodic peak currents (Ipa and Ipc) and steady peak-to-peak separation (ΔEp) across three independent batches, indicating excellent reproducibility with Ipa = 87.9 ± 1.7 μA, Ipc = −81.3 ± 1.5 μA, and ΔEp = 255.9 ± 4.6 mV for configuration A, and Ipa = 43.8 ± 0.6 μA, Ipc = −62.8 ± 1.2 μA, with a 3-fold lower peak separation (ΔEp = 87.6 ± 0.9 mV) in the case of configuration B (mean ± SE, n = 15). Primary benchmarking with similar commercial systems signifies the efficacy of WAST-produced transducers to mimic commercial electrode performance and provides a robust alternative to conventional deposition methods. In addition, a proof-of-concept experiment for Hg2+ ion sensing validated its potential for practical applications. The WAST method offers a robust fabrication, configuration choice, and tool-light patterning that can accelerate lab-scale prototyping of stand-alone flexible electrochemical devices.