Patent ID: 8212218

Claim:
A method for determining an amount of radiation, the method comprising: receiving the amount of radiation by a dosimeter, the dosimeter comprising a circuit, the circuit having a resonant frequency that is configured to change according to the amount of radiation received by the dosimeter, wherein the circuit comprises a varactor, the varactor comprising: a silicon substrate; and a dielectric layer located on top of the silicon substrate, wherein the amount of radiation causes a corresponding negative charge to build up in the dielectric layer, and the negative charge in the dielectric layer causes a depletion region to form in the silicon substrate underneath the dielectric layer, and wherein a capacitance of the varactor is reduced in response to the formation of the depletion region; absorbing radiofrequency (RF) energy by the dosimeter at the resonant frequency of the circuit from an RF transmitter; determining the resonant frequency of the circuit based on the absorbed RF energy; determining the capacitance of the varactor based on the determined resonant frequency; and determining the amount of radiation based on the capacitance of the varactor.