Advanced Medical Electronics Corporation (AME) and the University of Minnesota propose to develop a new graphene based continuous glucose monitor with passive wireless readout capability and dissolvable / biocompatible metallization layers for use in close-loop glucose control applications. Diabetes is the seventh leading cause of death in America and is likely to be underreported as a cause of death due to increases in other health problems caused by diabetes. Studies in the United States and abroad have found that improved glycemic control benefits people with diabetes. In general, every percentage point drop in A1C blood test results, for example, from 8.0 to 7.0 percent, can reduce the risk of microvascular complications-eye, kidney, and nerve diseases-by 40 percent. Development of treatment for patients with type-1 diabetes mellitus (T1DM) has advanced considerably in the past several decades to the point where the realization of an artificial endocrine pancreas (AEP) system consisting of a closed-loop plasma glucose monitoring system combined with an insulin delivery mechanism is now within reach. However, significant challenges remain in obtaining reliable, cost-effect, patient-friendly glucose monitoring systems. In this work, we describe a fundamentally new method of sensing glucose that has the potential to overcome numerous limitations of current CGMs, particularly regarding their size, invasiveness and inconvenience to the patient. The sensor is novel, because it is based upon a little-appreciated property of graphene called the quantum capacitance effect. Graphene is a two-dimensional allotrope of carbon that has numerous unique and extraordinary properties. The quantum capacitance effect in graphene allows the capacitance in a suitably-configured device to change when the electron concentration in the graphene changes. This allows graphene to act as an extraordinarily sensitive variable capacitor (varactor) whose capacitance can be tuned in response to the presence of a particular biomolecule, depending upon how the graphene surface is functionalized. If combined with an inductor, this device allows the glucose concentration to be encoded as the frequency shift of a passive resonator circuit. This sensing method has the potential to overcome the numerous limitations of conventional GCMs, as well as provide unique capabilities that are ideally suited for use in closed-loop artificial pancreas systems. In phase I, the feasibility of creating a disposable version of this sensor will be investigated by fabricating sensors where the graphene surface has been modified to be sensitive to glucose. Separate varactor and inductor designs will be created in order develop an estimate of the final device sizes that are possible. The feasibility of creating devices using biocompatible, dissolvable metals, such as magnesium, will also be investigated. The circuitry for wireless readout will also be developed and tested. AME has assembled an excellent team to develop this sensor and readout capabilities. In phase II, production prototype sensors and readout electronics will be built and tested on a patient population.
Continuous glucose monitors are a necessary component of closed-loop glucose control systems for treatment of diabetes mellitus. A simple, cost-effective wireless subcutaneous glucose sensing platform could provide enormous benefits for long-term diabetes mellitus patients utilizing closed-loop glucose control systems.
