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Sub-nanometer Resolution Imaging with Amplitude-modulation Atomic Force Microscopy in Liquid
Published on: December 20, 2016
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A review of demodulation techniques for multifrequency atomic force microscopy.
David M Harcombe1, Michael G Ruppert1, Andrew J Fleming1
1School of Electrical Engineering and Computing, The University of Newcastle, Callaghan, NSW, 2308, Australia.
Beilstein Journal of Nanotechnology
|January 25, 2020
Summary
This study compares atomic force microscopy demodulators, including lock-in amplifiers and filters, on an FPGA. Results show performance differences impacting higher harmonic imaging.
Area of Science:
- Physics
- Materials Science
- Nanotechnology
Background:
- Multifrequency atomic force microscopy (AFM) requires precise signal demodulation.
- Traditional demodulators may introduce artifacts or lack sensitivity.
Purpose of the Study:
- To compare the performance of various demodulators for multifrequency AFM.
- To evaluate sensitivity to frequency crosstalk and demodulation artifacts.
Main Methods:
- Implemented lock-in amplifier, coherent demodulator, Kalman filter, Lyapunov filter, and direct-design demodulator.
- Utilized field-programmable gate array (FPGA) with a 1.5 MHz sampling rate.
- Assessed performance across a range of demodulator bandwidths.
Main Results:
- Quantified sensitivity to other frequency components for each demodulator.
- Measured the magnitude of demodulation artifacts.
- Demonstrated performance differences using higher harmonic AFM imaging.
Conclusions:
- Performance variations among demodulators significantly impact multifrequency AFM imaging quality.
- The choice of demodulator is critical for minimizing artifacts and maximizing sensitivity in advanced AFM techniques.
