Abstract: In various aspects, the present disclosure provides an example autonomous microsystem for immersion into a fluid. The autonomous microsystem includes electronics, a power source, and a packaging system that surrounds the electronics and the power source. The electronics can be configured to sense and record one or more environmental conditions. The packaging system may include a deformable shell that defines an internal space and a plurality of filler particles disposed in the internal space and configured to control a density of the autonomous microsystem in relation to the fluid. The filler particles may comprise a low-density material having a bulk density greater than or equal to about 100 kg/m3 and less than or equal to about 1,000 kg/m3 and have a packing density greater than or equal to about 1011/m3 and less than or equal to about 1021/m3.

Abstract: A method is presented for tracking an ingestible device in a gastrointestinal tract of a subject. The method includes: measuring acceleration of the ingestible device as it traverses through the gastrointestinal tract, for example using an accelerometer disposed in the ingestible device; computing a metric from the acceleration measurements obtained by the accelerometer over a given period of time; and identifying a location in the gastrointestinal tract based in part on the metric.

Abstract: Investigating the permeability and porosity of geological samples is a routine element of geological studies, and is of particular interest in the oil and gas industry. Core-flood experiments are commonly performed on rock samples to measure transport characteristics in the laboratory. This disclosure reports the design and implementation of a high resolution distributed pressure measurement system for core-flood experiments. A series of microfabricated pressure sensors can be embedded in bolts that are housed within the pressurized polymer sheath that encases a rock core. A feedthrough technology has been developed to provide lead transfer between the sensors and system electronics across a 230-bar pressure difference. The system has been successfully benchtop tested with fluids such as synthetic oil and/or gas. Pressure measurements were recorded over a dynamic range of 20 bar with a resolution as small as 0.3 mbar.

Abstract: A capacitive sensor device is fabricated on a dielectric substrate. The capacitive sensor device may include multiple diaphragms that differ in shape and/or size. Each of the diaphragms is paired to upper and lower electrodes in included upper and lower electrode layers, respectively. The lower layer is on the dielectric substrate and couples the lower electrodes to a lower electrode terminal in parallel. The upper electrode layer is separated from the lower electrode layer by a gap defined by a removed sacrificial layer and couples the upper electrodes in parallel to an upper electrode terminal.