Patent ID: 8216519

Claim:
A hotplate chemical trace detector comprising: a heatable conducting plate comprising a heater element having a predetermined power—temperature characteristic relating a dissipated power in the heater element to a real temperature; a balancing circuit comprising an adjustable resistor for tuning the heater element to a predefined resistor value; a processor for adjusting the adjustable resistor so as to provide a stabilized temperature in said heatable conducting plate; a detection circuit for detecting a change of resistance in the heatable conducting plate in accordance with the presence of a chemical trace reacting in the presence of the conducting plate; and a test circuit for calculating the real temperature based upon a dissipated power in the heater element and the predetermined power—temperature characteristic, the test circuit comprising: a power measurement subcircuit adapted to measure the dissipated power in the heater element; a storage subcircuit adapted to store the predetermined power—temperature characteristic; and a calculating subcircuit coupled to the power measurement subcircuit, the calculating subcircuit adapted to determine the real temperature from the dissipated power measurement provided by the power measurement subcircuit and the predetermined power—temperature characteristic provided by the storage subcircuit.