Self-powered microneedle-based biosensors for pain-free high-accuracy measurement of glycaemia in interstitial fluid

In this work a novel self-powered microneedle-based transdermal biosensor for pain-free high-accuracy real-time measurement of glycaemia in interstitial fluid (ISF) is reported. The proposed transdermal biosensor makes use of an array of silicon-dioxide hollow microneedles that are about one order of magnitude both smaller (borehole down to 4 pm) and more densely-packed (up to 1 x 10(6) needles/cm(2)) than state-of-the-art microneedles used for biosensing so far. This allows self-powered (i.e. pump-free) uptake of ISF to be carried out with high efficacy and reliability in a few seconds (uptake rate up to 1 As) by exploiting capillarity in the microneedles. By coupling the microneedles operating under capillary-action with an enzymatic glucose biosensor integrated on the backside of the needle-chip, glucose measurements are performed with high accuracy ( +/- 20% of the actual glucose level for 96% of measures) and reproducibility (coefficient of variation 8.56%) in real-time (30 s) over the range 0-630 mg/dI, thus significantly improving microneedle-based biosensor performance with respect to the state-of-the-art. (C) 2014 Elsevier B.V. All rights reserved.