Model for a Thermoelectric Enzyme Glucose Sensor

A new calorimetric sensor that detects glucose through the change in enthalpy produced by an enzymatic reaction is mathematically modeled. The sensor is a thermopile attached to a membrane of immobilized glucose oxidase and catalase enzymes. The model predicts the temperature rise that occurs within the membrane in response to the concentration of glucose. The dependence of the modeled temperature rise on various conditions such as the oxygen concentration, external heat and mass transfer, and enzyme loading is supported with experimental data from a prototype sensor. The sensitivity of the sensor to glucose is characterized in terms of two quantities: Its initial value at low concentrations of glucose; and the range of response, specified as the concentration of glucose at which the sensitivity deviates from Its initial value by 10%. Each quantity is represented simply as a function of only two variables: an approximate Thiele modulus and the mass transfer Blot number. Each affects the two quantities in opposing directions. The initial sensitivity increases with an increase in Thiele modulus or a decrease in Biot number, whereas the range of response diminishes.