While ISF has significant promise for the measurement of analytes beyond glucose, a second challenge has been the generation of sensors that, unlike the enzymatic sensors used in glucose monitors, are independent of the chemical reactivity of their targets. That is, due to the modest number of oxidoreductive or other "sensor-ready" enzymes, enzymebased sensing approaches are not easily generalizable to most of the analytes accessible in ISF. Finding new sensing modalities has proven challenging, as any alternative to enzymatic sensors should maintain their many advantages, including their high measurement frequency and their ability to operate without the addition of exogenous reagents. Electrochemical aptamerbased (EAB) sensors, however, achieve these attributes while also relying on target binding rather than the chemical transformation of their target, rendering them as generalizable as the aptamers they employ for target recognition. And given that aptamer libraries start with trillions of randomly generated, potential aptamers which can then be further chemically modified to enhance their binding and tune it to invivo detection needs, the generalizability of aptamers appears broad .