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An innovative study at Cornell University explores utilizing an ultra-sensitive cantilever to measure weak thermal electric field gradient fluctuations over thin polymer films. By analyzing cantilever frequency fluctuations in various polymer compositions and thicknesses, the research applies a linear-response theory to quantify stochastic electric fields from dielectric fluctuations. The crystal silicon cantilevers, only 340 nm thick, exhibit remarkable force sensitivity down to the AttoNewton range, much lower than commercially available standards.
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AttoNewton Force Sensitivity for Measuring Dielectric Fluctuations Daniel C. Ralph, Cornell University, ECCS - 0335765 An ultrasensitive cantilever, oscillating parallel to a surface in vacuum, is used to probe weak thermal electric field gradient fluctuations over thin polymer films. The power spectrum of cantilever frequency fluctuations was measured as a function of cantilever height and voltage over polymers of various compositions and thicknesses. The data are well described by a linear-response theory that calculates stochastic electric fields arising from thermally driven dielectric fluctuations. The cantilevers were made of crystal silicon and are 340 nm thick, 250 µm long and 50-100 nm in diameter at their thinnest point. The spring constants of these cantilevers are as low as 10N/m, which permits detecting forces as small as an attonewton far below those available commercially. John Marohn and Nikolas Hoepker, Chemistry and Chemical Biology, Cornell University Work performed at Cornell NanoScale Facility
