Patent ID: 11946949
Assignee: TECHNISCHE UNIVERSITäT WIEN
Field: Measurement (Instruments)
Classification: CPC G  H | IPC G  H

Claim 3:
4. The method according to claim 3, wherein a difference signal is generated by a linear combination of the first comparison signal with a known temporally varying second comparison signal,
wherein the difference signal is filtered by at least one element acting as a low-pass filter, thus generating a filtered difference signal,
wherein the at least one sensor comprises a piezoresistive element and the sensor measurement variable is the electrical resistance of the piezoresistive element,
wherein the demodulation signal is an AC voltage signal and that the first comparison signal is generated by a voltage divider, wherein the voltage divider is formed from a first electrical resistance and a second electrical resistance, and wherein the second electrical resistance comprises the electrical resistance of the piezoresistive element
wherein
the second comparison signal is generated by a further voltage divider, which is formed from a third electrical resistance and a fourth electrical resistance, wherein the voltage divider and the further voltage divider are preferably part of a bridge circuit,
and wherein the first comparison signal and the second comparison signal are subtracted from one another to generate the difference signal
the filtered difference signal is amplified with a constant gain factor and then subtracted from a target value in order to form a control signal, wherein the control signal is fed to a scanner control in order to adjust the distance between a sample and the cantilever.