We report a refractive index (RI) sensor based on the use of vertically etched silicon Bragg reflectors. The device is robust and performs measurements through tens of micrometers of liquid. A sensitivity of 907 nm/RIU (RI units) and a resolution of 1.7×10−5 RIU are obtained and are in good agreement with optical simulations. This resolution is the highest reported for a volume RI sensor integrated with a microfluidic system. Expected applications for the sensor in the fields of single cell characterization and chip based liquid chromatography are discussed.
MEMS-scanning laser projector have seen tremendous performance improvements in the past year, demonstrating devices with very good performances in terms of size, energy efficiency and image quality that were expected from the theory point of view. The last challenge that was not solved yet is the speckle reduction, which is the main bottleneck for this technology adoption. The paper presents an innovative design to reduce speckle contrast without degrading any other features and benefits of the projection system. The proposed despeckling solution is a single, non-movable part with less than 0.1cc in volume and of 4mm in thickness.
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