Laser-induced graphene on the surface of carbon-coated 3D-printed microneedle arrays for minimally invasive electrochemical detection of olanzapine

We have developed a straightforward and scalable fabrication strategy to create laser-induced graphene on the tips of a carbon-coated 3D-printed microneedle array-based wearable electrochemical sensor to detect OZP in interstitial fluid. The device used a 3D-printed customized microneedle array, followed by spray coating of conductive carbon and silver inks to form the working, counter, and reference electrodes. Furthermore, the carbon-coated microneedle array-based working electrode was laser-treated to alter the surface into a graphitic structure for enhanced sensitivity. After physical and electrochemical characterization, the fabricated microneedle sensor was employed for detection of OZP. Under optimized settings, the microneedle sensor exhibited high sensitivity and specificity toward OZP, with a broad linear range of 0.05-500 µM and a lowest limit of detection of 0.0026 µM. The practical applicability was validated by detecting OZP in artificial interstitial fluid while penetrating a skin-like parafilm model and phantom gel matrix, which demonstrated the potential and practicability of the platform for minimally invasive monitoring of antipsychotic drugs. The obtained results highlight the feasibility of this cost-effective, scalable, and minimally invasive microneedle platform for monitoring OZP; this platform can also be readily adapted for the preparation of other wearable biosensors.