Cleanroom-Free Fabrication of Flexible Microneedle Array Patches for Minimally Invasive Monitoring of Dopamine

Abstract

The development of electrochemical sensors for detecting neurotransmitters using wearable electronics has recently gained significant attention due to their painless nature. However, such wearable electronics that enable topical sweat detection of neurotransmitters fall short in accuracy, as this does not reflect the actual physiological conditions. Interstitial fluid provides a more accurate and reliable medium for measuring neurotransmitter levels, closely paralleling those found in blood. In this scenario, the present work focuses on the development of flexible metal oxide-based microneedle array patches for minimally invasive detection of dopamine (DA). A polydimethylsiloxane (PDMS)-based microelectrode array was fabricated by transferring a master mold from a laser-punched stainless-steel template followed by Au sputtering. Next, the developed flexible electrode surface was modified with hydrothermally produced ZnO nanoparticles (ZNP) for DA detection. A 3 × 3 microneedle array platform showed sensitivity of 7.654 µA µM⁻¹ towards DA concentrations in a clinically relevant range of 1–100 µM in phosphate-buffered saline (PBS) electrolyte (pH 8). This proof-of-concept microneedle array platform could serve as an initial step towards the development of a painless and facile way of monitoring DA levels.