Our device is a low profile, minimally-invasive, wearable design in which the sensor remains ex-vivo and only FDA approved microneedles (from Nanopass Tech. Ltd.) enter the body (Figure ). These hollow, fluid-filled microneedles create a coupling that allows the analyte to rapidly diffuse to the sensor. This coupling also acts as a failsafe for immediate detection of failed insertions; without the fluidic connection between the sensor and the dermis the device does not pass measurable currents. The device is relatively simple to construct: a gold working electrode modified with the target-recognizing aptamer is sealed against the microneedles (figure ) and then surrounded by a gel Ag/AgCl counter electrode that covers the surrounding skin surface. The fabricated device is placed onto the arm and gentle pressure is applied by hand to ensure microneedle penetration (no specialized "inserter" is required). In this work, we attached the electrodes to a bench-top potentiostat, and then employed square wave voltammetry to interrogate the sensor. With the addition of a miniaturized potentiostats , this approach could readily be adapted to a fully self-contained, wearable device supporting continuous, realtime molecular monitoring (figure &).