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Piezo-generated charge mapping revealed through direct piezoelectric force microscopy
A. Gomez, M. Gich, A. Carretero-Genevrier, T. Puig & X. Obradors
Nature Communications 8, Article number: 1113 (2017)


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Atomic force microscopyCharacterization and analytical techniquesElectronic properties and materialsScanning probe microscopy
21 September 2016
12 September 2017
Published online:
24 October 2017

A team of researchers have created a new Atomic Force Microscope with the help of Analog Devices electronics. In particular, they measure the tiny currents produced by the piezoelectric effect with a transimpedance amplifier, which consists into a current-to-voltage converter. The work entitles “Piezo-generated charge mapping revealed through direct piezoelectric force microscopy” published in the prestigious scientific journal Nature Communications.

The amplifier required to measure such tiny currents is only offered by Analog Devices Inc, with part number ADA4530. Such component consists of a Femtoampere Input Bias Current Electrometer Amplifier populated with a 1 TeraOhm resistor as a feedback resistor in a transimpedance configuration. Throughout the measurements, reducing the ambient humidity of the electronics box was a key factor, while working at the maximum allowed bias was intended to diminish the ultra-low input bias current of the ADA4530. An additional voltage amplifier, with the inverting amplifier topology, is located at the output of the transimpedance, using an ADI AD8429. With such tandem of amplifiers, researchers were capable of measuring the generated charge of several piezoelectric materials directly.

The research focused into the mapping of Piezogenerated charge of a piezoelectric material. Piezoelectricity is a property where a charge is generated by a material as a consequence of a mechanical stress applied to the material. In this particular research, the material is stressed by a tiny needle, an AFM tip with nanometric size. The tip applied a force in the range of 100 microNewton and measures the generated charge that is created into the material. The total charge collected for each material was 5fC for Periodically Poled Lithium Niobate, 25 fC for Bismut Ferrite and 90fC for Lead Zirconate Titanate. This new mode enhances Atomic Force Microscopy as a key future technique available for material research and opens a future into counting electrons at the nanoscale.

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