Bench Talk

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For their size, micro-electromechanical systems (MEMS) are making a large impact in medicine.

MEMS have a wide range of applications but have a distinct value in the medical sector. Among their uses are temperature sensors, pressure sensors, flow sensors, acoustic sensors, gas sensors, and image sensors. The configurations of MEMS-based devices vary from those with no moving parts to those with many moving components.

The use of MEMS technology has become an integral part of patient monitoring. For instance, MEMS technology is essential for measuring intravascular blood pressure. Disposable pressure sensors used in IV lines of intensive care patients account for the largest market for MEMS pressure sensors. Additionally, MEMS pressure sensors are widely used in ventilators to monitor the patient’s breathing.

More recently, MEMS sensors are marketed for their wireless interrogation capability. These sensors can be implanted into the human body and the pressure measured remotely using a scanned wand.

The small size, accuracy, and reliability of MEMS sensors also makes them ideal for wearable devices. Various kinds of MEMS inertial sensors are used as activity sensors, including accelerometers and rate sensors.

Of course, this is only a partial accounting of MEMS-based applications. More use cases are being frequently developed by product designers.

In this week's New Tech Tuesdays, we'll look at a pressure sensor kit from STMicroelectronics and a MEMS accelerometer from Analog Devices Inc.

The STMicroelectronics STEVAL-MKI228KA Pressure Sensor Kit is a two-piece evaluation kit with Qvar functionality based on the ILPS22QS pressure sensor, which is soldered exactly at the board's center. The kit provides the complete ILPS22QS pin-out and comes ready to use with the required decoupling capacitors on the V_DD power supply line. The kit consists of the STEVAL-MKI228A and the STEVAL-MKE001A. The STEVAL-MKI228A mounts the ILPS22QS pressure sensor with the Qvar electrostatic sensor and swipe electrode making it compatible with the STEVALMKI109V3. The ILPS22QS embeds analog hub sensing used to implement the Qvar technology, which is critical for water leakage detection.

Analog Devices Inc.'s ADXL373 Micropower 3-Axis MEMS Accelerometer is an ultra-low power, 3-axis, ±400g MEMS accelerometer that consumes 19µA at 2560Hz and can be powered from a coin cell battery. With its low g threshold activity and inactivity detection, the ADXL373 can perform low-power event monitoring, detects impacts, and wakes up fast enough to capture transient events. The device switches to the normal operating mode when an impact exceeds a set threshold. Examples of medical applications include impact and shock detection, asset health assessment, and concussion and head trauma detection.

The applications for MEMS systems are numerous, but their impact has been largely felt in the medical industry. As the technology evolves, as it has been for decades, expect even more innovations from product designers.