Fabrication of Low-Invasive Patch Glucose Sensors

Tuesday, October 13, 2015
West Hall 1 (Phoenix Convention Center)
J. Li (Tokushima University), K. Hiura (Tokushima University), M. Yasuzawa (Tokushima University), and Y. Fuchiwaki (Health Research Institute, AIST)
1. Introduction
Recently, implantable glucose sensors for continuous glucose monitoring (CGM) are provided significant advantage on diabetic health care, since it not only lower the physical and mental load on glucose measurement, but also present continuous glucose trend, which is useful for treatment evaluation. However, since the length of sensor device inserted in skin is about 1 cm, development of lower invasive CGM system is expected for the improvement of diabetic patients' quality of life.
In this study, a fine needle tube type glucose sensor, which has sensing region at the tip of a fine tapered electrode, was proposed. The schematic illustration of such glucose sensor is shown in Fig. 1. Since the sensing region is at the tip of tapered electrode, it only requires the sensor tip to be implanted in the tissue for glucose monitoring, which makes it possible to perform as a patch type sensor instead of implanting sensor. Fine platinum-iridium alloy wire was placed inside the tapered PEEK tube and glucose oxidase (GOx) was immobilized on the surface of platinum electrode by using the combination of electrodeposition and electropolymerization technique. Properties of the obtained sensor were evaluated mainly by in vitro measurement.
Pt-Ir alloy wire (0.17 mm in diameter) was fixed in a PEEK tube (0.20 mm in inner diameter and 0.8 mm in outer diameter). The prepared assembly was mechanically polished to form a fine tapered needle structure. According to the procedure proposed by Wilson's group [1], the biosensor was prepared.
The amperometric responses of the prepared electrodes to glucose were examined at 40°C in a 0.1 M PBS (pH 7.4) containing 0.1 M NaCl, by measuring the electrooxidation current at a potential of 0.6 V (vs. Ag/AgCl).
Current-time response of the prepared electrode was investigated. The response current increased with increasing concentration of glucose. Response current provided good linear relationship with glucose concentration. Variation of response in time on the prepared electrode was investigated for two weeks. The response of the electrode was measured at 40°C and stored in phosphate buffer at 4°C when not in use. After initial increase of response current for few days, the electrode provided stable response current.
(1) N. Matsumoto, X. Chen and G. S. Wilson, Anal Chem, 74, 368 (2002).