Implantable glucose biosensors for continuous glucose monitoring (CGM), are getting more attractive, since they can provide greater insight into the direction, magnitude, duration, frequency and possible causes of glucose fluctuations in response to meals, insulin injections, hypoglycemic episodes and exercise throughout the day. The current commercialized or presented conventional CGM sensor devise are required to have about 1.0 cm in length to be inserted inside the skin. Therefore, it is expected to develop lower invasive type glucose sensor in order to improve the life-quality of diabetic patients.　We have previously reported that the sensor response of a fine tapered needle type glucose sensor, which has a sensing region at the tip, showed good correlation with blood glucose value, even it was implanted in the skin of a rabbit for a length of 1.0 mm [1]. This indicate that the glucose measurement in dermis may provide valuable information comparable to subcutaneous tissue glucose measurement. As part of our low-invasive improvement of the sensor, miniaturization of sensing region is essential, but it may lead to a decrease of response current to glucose. Therefore, at the same time, the improvement of sensor sensitivity is also indispensable. The sensitivity of an enzyme based glucose sensor can be improved by introduction of carbon nanomaterial or mediator, which can increase electrode surface area and the efficiency of electron or mass transport to the transducer. Due to their high chemical stability, high surface area, and unique electronic properties, carbon nanotubes (CNT) and graphene has greatly increased biosensor sensitivity and response speed. On the other hand, electroetching of the electrode surface is an effective method to obtain a higher surface area, which may be responsible for enhanced sensitivity. In this study, introduction of carbon nanomaterial and electroetching technique were introduced to improve the sensitivity of the proposed glucose sensor.

[1] J. Li, P. Koinkar, Y. Fuchiwaki, M. Yasuzawa, Biosens. Bioelectron., 86 (2016) 90.