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8 Platform one Flusso, a semiconductor company spun out of the University of Cambridge, has developed a gas flow meter that is smaller and less expensive than others on the market (writes Nick Flaherty). It uses a MEMS micromachined combination of heaters and sensors to measure the flow, and can be used in fuel cells and engines to monitor the flow of hydrogen. It is packaged and assembled using a standard chip process that allows manufacturing in tens of millions of parts per month. Its small size, 3.5 mm, allows more flow meters to be installed across an unmanned system to provide more data. The flow meter uses hot-film sensors that are fabricated using a 1 µm silicon- on-insulator (SOI) CMOS chip-making process in a commercial foundry. After the CMOS process, a Deep Reactive Ion Etching (DRIE) process is used to create cavities under a membrane to further increase the thermal isolation of the hot-film sensors. DRIE creates cavities with vertical side walls, as it does not depend on the lattice orientation of a silicon substrate. This Raptor Photonics has launched an InGaAs-based SWIR camera with a 640 x 512 resolution that detects visible light as well as short-wave infrared by using a 10 x 10 µm pixel pitch (writes Nick Flaherty). The Owl 640T has less than 50 electrons of readout noise and an intra- scene dynamic range of 69 dB. This enables simultaneous capture of bright and dark portions of a scene across 0.6 creates more consistent heating for the measurements. The SOI technology provides various advantages. The buried oxide insulator layer acts as an etch-stop layer for the DRIE process, controlling the etch depth. It provides a uniform thickness for all sensor membranes, and thermally isolates the sensing area to reduce the power losses to the silicon substrate. It also electrically isolates the to 1.7 µm, and allows frame rates of up to 120 Hz. “The key to the camera’s technology is essentially the sum of all its parts,” said Mark Donaghy, a technical expert at Raptor. “This includes the low- noise electronics, the SWaP features, ruggedness and firmware features with auto-gain control. “We also offer a range of OEM options such as a choice of camera interface, board layout, cooling and so on.” electronic circuitry, reducing crosstalk, and increases the device’s operating temperature range. “The energy efficiency of many products could be greatly improved if they incorporated gas and flow sensors, but companies cannot do that owing to cost, size or manufacturing constraints,” said Andrea De Luca, founder and CEO of Flusso. “We want to bring flow and gas sensing technologies to these products.” Fuel monitoring Imaging Tiny flow meter unveiled Owl offers dual vision Flusso has built this miniature gas flow meter using standard chip-making technology Raptor’s Owl 640T has a readout noise of less than 50 electrons August/September 2020 | Unmanned Systems Technology