Abstract-In this paper, we present a new method for detecting in-plane displacements in microelectromechanical systems (MEMS) with an unprecedented sub-ångström accuracy. We use a curve-fitting method that is commonly employed in spectroscopy to find peak positions in a spectrum. We fit a function to the intensity profile of the image of a silicon beam that was captured with a CCD camera on an optical microscope. The position resolution depends on the amount of pixel noise and on how the moving feature is spread across the detector pixels. The resolution is usually limited by photon shot noise, which can be controlled and lowered in several ways. To demonstrate the technique we measure the adhesion snap-off of two silicon surfaces. We assess the accuracy of the technique using two different silicon MEMS devices and an experimental ultrananocrystalline diamond device. The lowest position noise that we report is obtained by summing 1 577 image lines and is as low as 60 pm root mean square.[ 2014-0040]Index Terms-Displacement measurement, optical noise, optical image processing, optical position measurement, MEMS, subpixel resolution.

Clinical laboratory-based nucleic acid amplification tests (NAT) play an important role in diagnosing viral infections. However, laboratory infrastructure requirements and their failure to diagnose at the point-of-need (PON) limit their clinical utility in both resource-rich and -limited clinical settings. The development of fast and sensitive PON viral NAT may overcome these limitations. The scalability of silicon microchip manufacturing combined with advances in silicon microfluidics present an opportunity for development of rapid and sensitive PON NAT on silicon microchips. In the present study, we present rapid and sensitive NAT for a number of RNA and DNA viruses on the same silicon microchip platform. We first developed sensitive (4 copies per reaction) one-step RT-qPCR and qPCR assays detecting HCV, HIV, Zika, HPV 16, and HPV 18 on a benchtop real-time PCR instrument. A silicon microchip was designed with an etched 1.3 μL meandering microreactor, integrated aluminum heaters, thermal insulation trenches and microfluidic channels; this chip was used in all on-chip experiments. Melting curve analysis confirmed precise and localized heating of the microreactor. Following minimal optimization of reaction conditions, the bench-scale assays were successfully transferred to 1.3 μL silicon microreactors with reaction times of 25 min with no reduction in sensitivity, reproducibility, or reaction efficiencies. Taken together, these results demonstrate that rapid and sensitive detection of multiple viruses on the same silicon microchip platform is feasible. Further development of this technology, coupled with silicon microchip-based nucleic acid extraction solutions, could potentially shift viral nucleic acid detection and diagnosis from centralized clinical laboratories to the PON.

a b s t r a c tIn this study, we have investigated the adhesion phenomena between two sidewalls in boron-doped ultrananocrystalline diamond (B-UNCD) micro-electro mechanical systems (MEMS) in a humid and dry environment. We have developed and built B-UNCD MEMS test devices, in order to assess the tribological properties of diamond micro devices in-situ. Using these devices, we have been able to measure the adhesion force with approximately 15 nN resolution, by monitoring the displacement optically with a precision of 4 nm. In the case of testing in a dry atmosphere, virtually no adhesion (b 18 nN) was observed between the sidewalls. After testing in humid air over 55,000 cycles, increased adhesion force up to 128 nN was measured. A rare observation of capillary neck formation between sidewalls at high contact force, in humid air is observed which is most probably caused by the precipitation of carbon contamination. This contamination layer can be easily removed by oxygen plasma exposure but thereafter highest adhesion force of 260 nN adhesive force was measured. Our studies demonstrate that micromechanical devices fabricated based on diamond represent a great alternative over polysilicon based devices in terms of reduced adhesion and thus long term reliability, which is a significant step forward in developing diamond based MEMS.

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