Low-cost amplifier design for a cooled Scanning Probe Microscope

To further our understanding of 2D materials, it’s crucial to investigate them at the nanoscale. This would shed light on the physics of such materials and helps us develop better electronic and photonic devices. One way to do this is to use a cooled Scanning Probe Microscope (SPM). To image quantum properties of such 2D materials, a SPM tip is raster scanned over the sample while measuring its local electronic properties. In such a system, the feedback mechanism plays an important role in making such measurements. For such feedback systems, low noise/high-gain amplifiers are essential. Unfortunately, such amplifiers are expensive and increase the price of the overall system. We present the design of low-cost amplifier system for such cooled SPM system. Our amplifier design consists of a Wheatstone bridge circuit to detect a voltage change across the SPM cantilever. The signal from Wheatstone bridge is amplified by using a cascade of low-cost operational amplifiers set to high gain and low noise mode. Such system would allow for low budget AFMs making it more accessible by saving a several thousand dollars on commercial amplifiers.