| Diabetes mellitus is a chronic disease that is brought about by either the insufficient production of insulin or the inability of the body to respond to the insulin formed within the system. Diagnosis and blood glucose control of patients with diabetes often need to detect the concentration of glucose in the blood. Study of glucose biosensors have become a very important research direction in the field of biosensors. After decades of efforts of researchers in China and abroad, study of glucose biosensor has made tremendous progress. Home glucose test strips and short term continuous glucose monitoring have been realized. However, the convenience, stability, reliability, long-term and real-time detection properties of glucose sensors are still face great challenges. Research and development of new glucose biosensors based on new material, new technology and new process are still the focus of current research work.New materials are the basis to promote the development of sensors. Graphene, a two dimensional carbon nano material, has good conductivity, large surface area, and good mechanical properties, showing a good application prospect in the field of electrochemical biosensor. However, graphene sheets are easy to agglomerate and difficult to disperse, graphene film forming dense structure, which limits the application in electrochemical biosensors. Aiming at these problems, this thesis focused on the study of electrochemical reduction technology of carboxyl graphene and its application in the direct electron transfer of glucose oxidase, the preparation technology of graphene and silk fiber composite film material and its application in flexible glucose biosensor. What’s more, a planar microelectrode glucose sensor has been fabricated and integrated with a potentiostat circuit and a wireless communication circuit for the realization of a fully implantable device.The main research contents and innovations are as follows:(1) Carboxyl graphene was electrochemically reduced, and characterized with several analysis technologies. The results show that, the electrochemical reduction technology can improve the electrical conductivity.(2) ERCGr/GCE was prepared by electrochemical reduction method. Glucose oxidase (GOx) was immobilized by covalent binding to ERCGr surface. Results show that GOx on the surface of ERCGr/GCE can achieve the direct electron transfer and show electrochemical catalytic response to glucose.(3) We proposed a preparation method of conductive fiber by wrapping graphene on silk fiber. Results show that the graphene coated silk fiber has good conductivity, flexibility and bending properties, which has a good application prospect in wearable electronics equipment, flexible wires, flexible electrodes etc..(4) We proposed a preparation method of graphene/silk (G/S) composite films. The G/S composite film has two different sides. The top side possesses porous network structure, while the bottom side has compact film structure, good electrical conductivity and mechanical strength.(5) The G/S composite films were modified Pt nanospheres by electrochemical deposition. Electrochemical tests show that the spiky Pt nanospheres decorated G/S film has a good catalytic performance to H2O2. A glucose biosensor electrode was further fabricated by enzyme immobilization by crosslinking with glutaraldehyde. Results show a sensitivity of 150.8 μA mM’1 cm-2 and a low detection limit of 1 μM (S/N=3) for glucose detection.(6) We designed a potentiostat circuit and a MICS band low power short distance wireless communication circuit. We fabricated a planar microelectrode for glucose sensor with microelectronic manufacturing process. The linear detection range of 0～30 mM, sensitivity is 2.2 μA mM-1 cm-2. Finally, we integrated the microelectrode with the circuit board. The total volume of the glucose biosensor system is only 0.76 cm3. |
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