A patch type non-enzymatic biosensor based on 3D SUS micro-needle electrode array for minimally invasive continuous glucose monitoring

We developed a new patch-shaped enzyme free biosensor using a micro-needle array with Pt black sensing electrode layer for painless continuous glucose monitoring applications. We fabricated the micro-needle array using a bulk micromachining technique and commercial stainless steel 316L grade substrate. Pt black and Ag/AgCl were then electroplated on the tip of each micro-needle as working and counter/reference electrodes of the sensor, respectively. The fabricated micro-needle was 650 mu m high and 150 pm wide. We used 48 and 24 micro-needles for the working electrode and counter/reference electrode, respectively. The measured sensitivity was 1.62 mu A mM(-1) with high linearity of 0.9939, and was obtained within 13 sec, in glucose concentrations ranging up to 36 mM. The biosensor also exhibited a low detection limit of 50 mu M. We tested the sensor under PBS solution over a period of 6 days. Then we partially inserted the sensor into a rabbit, to monitor the interstitial glucose level. We then induced change of interstitial glucose concentration by oral glucose tolerance test. Although we expected the sensor to perform for more than 6 days, it performed for just 4 days as a sensor, due to bio fouling. (C) 2015 Elsevier B.V. All rights reserved.