Microneedles with Recessed Microcavities for Electrochemical Sensing in Dermal Interstitial Fluid

Transdermalelectrochemical sensors based on microneedle (MN) orMN array technology are the next frontier of personalized wearabledevices in health monitoring and diagnostics. The performance of transdermalsensors is impacted mainly by damage or deformation of the sensinglayer located on the MN surface, which usually occurs due to frictioncaused between the MN surface and skin tissue. In this work, we reportthe development of a 4 x 4 polymeric MN array (PMNA) with anindividual MN height of similar to 720 mu m and integrated conductiverecessed microcavities (MC) on the MNs surface to protect the sensinglayer during insertion and removal from the skin. Characterizationand proof-of-concept experiments on porcine skin reveal that PMNA/MC-basedplatforms retain their functionality and sensitivity of 2.36 +/- 0.06 nA mM(-1) even after multiple skin applications.Three-dimensional nanostructuring of MNA hence provides alternativesolutions to the critical issues of maintaining performance upon insertioninto skin. This approach holds great potential in advancing transdermalsensing technology and affording reliable, cost-effective, and clinicallyadequate sensing devices.