Many fields of science require the monitoring of analyte concentrations in fluids. In an example of insulin-treated diabetes, afflicted persons must frequently monitor their blood glucose levels in order to appropriately ascertain the dose of insulin. Without an accurate measurement, insulin dosing would be dangerous.
Multiple devices have been devised for the measurement of analytes in fluid. Devices such as electrochemical sensors utilize electrodes coated with polymer membranes. The functions of such sensors can be manipulated depending on which materials are used and in what quantities so that necessary reactions are controlled. Depending on the reaction near the electrodes, changes in current can be measured and thus correlated to the analyte of interest.
The measurement of glucose in human blood makes use of electrochemical sensors. Sensors of this design measure blood glucose from samples drawn from a patient. In the case of diabetic patients, these samplings often occur several times per day. The sampling process, which equates to a finger prick, can be uncomfortable as well as difficult. Since blood sampling requires specially designed equipment, diabetic patients must have them readily available and thus carry their supplies with them at all times. Due to this cumbersome process, some patients fail to sample their blood as often as they should. Fortunately, an implantable glucose sensor would solve the problem of infrequent blood samplings.
Current implantable sensor designs have many problems that must be addressed before such a device can come to market. Constant subcutaneous or vascular access must be attained for a sensor to constantly measure glucose levels. Due to discomfort and the possibility of infection, wires protruding from the skin are undesirable. A completely implantable sensor that communicates with an external receiver through wireless transmission would solve this problem. Unfortunately, an implantable sensor could result in internal trauma if the sensor is especially large or inappropriately shaped. Also, a patient's body could interpret an implanted sensor as a foreign object and attempt to either destroy or isolate it. If either of these actions were successful, the analytes of interest could not be monitored. Sadly, all attempts thus far have failed in the long-term due to these issues.