The sensor detects the current on electrodes, which is proportional to glucose in tissue fluid. And the linear relation of the two can be described as the current-glucose concentration function: current=K [glucose concentration] +B.

 The slope (K) and the intercept (B) of the line are the correlative coefficients of the two. The environment of tissue fluid is different from that of in vitro testing, so the sensitivity (slope) of the sensor in these two environments are different, and the background current (intercept) in tissue fluid cannot be replaced by in vitro intercept. In other words, because of the particularity of tissue fluid, the slope (K) and the intercept (B) of the sensor must be determined under the testing person’s real condition.

 For practical purposes, glucose should be tested with a known standard device (glucose meter); that way, the value and corresponding current at that moment can be put into the formula, such that the slope and intercept of this point can be calculated. When the sensor is stable enough (its slope and intercept do not change with time), the calculated slope and intercept can represent the characteristic of the sensor for a certain period of time, and can be used to calculate the conversion between current and glucose.

The aim of calibration is to calculate the current-glucose conversion, and transform current value into glucose value.(Should this come first?)