MEMS Accelerometers

Micro-electro-mechanical system (MEMS) devices are widely used for inertia, pressure, and ultrasound sensing applications. Research on integrated MEMS technology has undergone extensive development driven by the requirements of a compact footprint, low cost, and increased functionality. Accelerometers are among the most widely used sensors implemented in MEMS technology. MEMS accelerometers are showing a growing presence in almost all industries ranging from automotive to medical. A traditional MEMS accelerometer employs a proof mass suspended to springs, which displaces in response to an external acceleration. A single proof mass can be used for one- or multi-axis sensing. A variety of transduction mechanisms have been used to detect the displacement. They include capacitive, piezoelectric, thermal, tunneling, and optical mechanisms. Capacitive accelerometers are widely used due to their DC measurement interface, thermal stability, reliability, and low cost. However, they are sensitive to electromagnetic field interferences and have poor performance for high-end applications (e.g., precise attitude control for the satellite). Over the past three decades, steady progress has been made in the area of optical accelerometers for high-performance and high-sensitivity applications but several challenges are still to be tackled by researchers and engineers to fully realize opto-mechanical accelerometers, such as chip-scale integration, scaling, low bandwidth, etc

Thermoresistive Strain Sensor and Positioning Method for Roll-to-Roll Processes

This study uses the Joule heating effect-generated temperature difference to monitor in real-time and localize both compressive and tensile strains for the polymer substrates used in the roll-to-roll process. A serpentine gold (Au) line was patterned on a polyethylenenaphthalate (PEN) substrate to form the strain sensor based on thermoresistive behavior. This strain sensor was then subjected to either current or voltage to induce the Joule heating effect on the Au resistor. An infrared (IR) detector was used to monitor the strain-induced temperature difference on the Au and PEN surfaces and the minimal detectable bending radius was 0.9 mm with a gauge factor (GF) of 1.46. The proposed design eliminates the judgment ambiguity from conventional resistive strain sensors where resistance is the only physical quantity monitored. This study precisely and successfully indicated the local strain quantitatively and qualitatively with complete simulations and measurements

Thermoresistive Strain Sensor and Positioning Method for Roll-to-Roll Processes

This study uses the Joule heating effect-generated temperature difference to monitor in real-time and localize both compressive and tensile strains for the polymer substrates used in the roll-to-roll process. A serpentine gold (Au) line was patterned on a polyethylenenaphthalate (PEN) substrate to form the strain sensor based on thermoresistive behavior. This strain sensor was then subjected to either current or voltage to induce the Joule heating effect on the Au resistor. An infrared (IR) detector was used to monitor the strain-induced temperature difference on the Au and PEN surfaces and the minimal detectable bending radius was 0.9 mm with a gauge factor (GF) of 1.46. The proposed design eliminates the judgment ambiguity from conventional resistive strain sensors where resistance is the only physical quantity monitored. This study precisely and successfully indicated the local strain quantitatively and qualitatively with complete simulations and measurements

Development of a Novel MEMS Thermal Sensor Array for Pebble Bed HTGRs

A novel high temperature thermal instrument is proposed, which utilizes a dual-sensing platinum resistor encased in a mono-crystalline alpha-alumina (sapphire) substrate. The instrument is comprised of four platinum trace elements, oriented with 90° rotational symmetry atop a 1120 oriented crystal lattice substrate. All four of these sensors measure temperature directly via 4-wire ohm measurement of the absolute resistance, while two sets of orthogonal sensors measure the differential strain created by the axially dependent thermal expansion coefficient of a sapphire substrate via a WSB measurement. The RTD temperature measurement calibration is then monitored for drift and corrected by comparing the differential strain-derived measurement of temperature to the temperature derived from the RTD measurement. This allows the instrument to self-calibrate via comparison of two functionally independent measures of electron mobility and operate in extreme environments which have previously caused RTD sensors to drift from their initial calibration and introduce an undefined measurement error. The intended deployment configuration and instrument construction is defined in terms of MEMS fabrication processes and performance of the sensor is simulated to evaluate and confirm the functional applicability of the instrument for operation in pebble bed HTGR thermal environments

Data Acquisition Applications

Data acquisition systems have numerous applications. This book has a total of 13 chapters and is divided into three sections: Industrial applications, Medical applications and Scientific experiments. The chapters are written by experts from around the world, while the targeted audience for this book includes professionals who are designers or researchers in the field of data acquisition systems. Faculty members and graduate students could also benefit from the book