Here is a sneak peek into the most prominent MEMS devices incorporated into designs to bridge the gap between analog and digital.
MEMS integrates both active and passive components into a single silicon substrate with the help of advanced IC manufacturing technology. MEMS sensors are what connects the analog world around us to the digital world of processing and computing. A MEMS sensor is like our human eyes, ears, nose, mouth and skin with touch sensing.
The global MEMS market is growing well toward a $35 billion forecast by 2024. Here is a sneak peek into the most prominent MEMS devices in 2021.
Vesper’s VM3011 adaptive zero-power listening (ZPL) digital piezoelectric MEMS microphone, rated for harsh environments, automatically adjusts its acoustic threshold based on the background level of environment noise. This device has excellent system power savings, enabling extended battery life with no compromise in acoustic performance.
The VM3011 device delivers high acoustical performance via a bottom port digital MEMS microphone in an industry-standard package size of 3.76 x 2.95 x 1.3 mm. The microphone integrates an ASIC and a piezoelectric MEMS transducer into the package. A digital pulse density modulation (PDM) interface is available to stream the audio data, while an I2C interface allows on-the-fly configuration of the adaptive ZPL capability.
The Flusso FLS110 is an analog mass flow sensor. The sensor is combined with a standard microcontroller and firmware that enable digital flow sensing solutions. The device is housed in a small 3.5 mm x 3.5 mm package and has a repeatability of 0.5 sccm (standard cubic centimeter per minute) with +0.5% measured value. Flow is measured to 500 slm (standard liter per minute) or more and is temperature-compensated for a reliable flow signal. An evaluation kit enables designers to test the FLS110 with a ready-made flow fixture and a GUI that runs under Windows 10.
The TDK CH-101 is based on Chirp’s patented MEMS technology. It’s a system-in-package (SiP) that integrates a piezoelectric micromachined ultrasonic transducer (PMUT) with an ultra-low-power system-on-chip (SoC) in a small, reflowable package.
The SoC uses Chirp’s advanced ultrasonic DSP algorithms and includes an integrated microcontroller that facilitates digital range readings via I2C. The sensor enables accurate range measurements to targets at distances up to 1.2 m. This time-of-flight (ToF) range sensor can also measure distances between people instantaneously.
The Conamara UT-P4010 speaker is IPX8 waterproof and can be safely submerged in water up to 3 meters in depth for 30 minutes. The device has a robust sound pressure level (SPL) with low total harmonic distortion (THD). Uses are in-ear audio designs like wired earphones or even true wireless stereo (TWS) in which there are no wires to connect earbuds to phone or even to each other.
Imec has developed a MEMS-based optomechanical ultrasound sensor on a silicon photonic chip with a robust sensitivity credited to an innovative optomechanical waveguide. This 20-µm sensor has a detection limit two orders of magnitude better than piezoelectric elements of identical size. This low detection limit enables innovative clinical and biomedical applications for ultrasonic and photoacoustic imaging like deep-tissue mammography.
The MEMS device also allows the study of vascularization or innervation of potential tumorous tissue. It’s based on a highly sensitive split-rib optomechanical waveguide fabricated using a new CMOS-compatible processing mechanism.
Indoor air quality strongly affects our health and well-being as well as the risk of viral infections such as COVID-19 via aerosols in our breath. The Bosch BME680 sensor has been developed to detect exhaled human breath and output an air quality index. Humidity makes it easy for a virus to connect as cold air enables virus survival, and high amounts of exhaled air from lungs and aerosols lead to virus infection if someone is affected.
The device cannot detect the Coronavirus, but it can measure the amount of used air; concentration-controlled ventilation can reduce infection. An air quality ‘stoplight’ can indicate when to air the room using BME680, which will reduce the risk of viral infection. Designers can integrate this solution into smart LED lights, which can change color (green-yellow-red), indicating when air quality is not good. Schools and college classrooms will benefit from this device especially.
The LIS2DTW12 has user-selectable full scales of ±2g/±4g/±8g/±16g and can measure accelerations with output data rates from 1.6 Hz to 1,600 Hz. The device also has an embedded 0.8°C (Typ. accuracy) temperature sensor with output data rates (ODRs) ranging from 50 Hz to 1.6 Hz and resolution from 8 to 12 bits.
There is an integrated 32-level first-in-first-out (FIFO) buffer that allows the user to store data to limit intervention by the host processor. Moreover, it has an embedded self-test capability for users to check the functioning of the sensor in the final application. Packages are available in a small thin plastic land grid array (LGA) package and the device is guaranteed to operate over an extended temperature range from -40°C to +85°C.
The ADXL1001/ADXL1002 MEMS devices have ultra-low noise density over an extended frequency range with two full-scale range options optimized for industrial condition monitoring. The ADXL1001 (±100 g) and the ADXL1002 MEMS sensors have typical noise densities of 30 µg/√Hz and 25 µg/√Hz, respectively. Both accelerometer devices have stable and repeatable sensitivity, immune to external shocks of up to 10,000 g.
The MEMS sensors have an integrated full electrostatic self test (ST) function and an over range (OR) indicator that enables advanced system-level features for embedded applications. With low power and single-supply operation of 3.3 V to 5.25 V, the devices enable wireless sensing product designs. They are available in a 5 mm × 5 mm × 1.80 mm LFCSP package and are rated over a −40°C to +125°C temperature range.
The model AXISENSE-G, a dual-axis tilt sensor, combines signals from a MEMS multi-axis accelerometer and multi-axis gyro into an accurate representation of pitch-and-roll angles. The gyro improves the reaction time of the sensor and reduces susceptibility to shock and vibration events. The sensor uses gravity as a reference and reports any positive or negative tilt angle in both the X and Y axes. Static accuracy for the measurements is ±0.5°.
The device is packaged in a rugged enclosure and is immune to harsh environments. It has an IP-67 rating for outdoor uses. The sensor has a 400 mm (15.7”) integrated cable and a 4-pin sealed, keyed, latching connector. It has a wide supply voltage range of 8–36 VDC and built-in temperature sensor and self-diagnostic features that immediately notify the user or system of any problems.
The SiT5157 device is a ±0.5 ppm to ±2.5 ppm MEMS Super-TCXO with unique DualMEMS temperature sensing and TurboCompensation technologies. The IC delivers robust dynamic performance for timing stability in the presence of environmental stressors like airflow, temperature perturbation, vibration, shock, and electromagnetic interference. The MEMS device also integrates multiple on-chip regulators to filter power supply noise, eliminating the need for a dedicated external LDO. The output capability is 60–189 MHz and 208–220 MHz in 1-Hz steps.
This article was originally published on Planet Analog.
Steve Taranovich is a senior technical editor at EDN with 40 years of experience in the electronics industry. Steve received his MSEE from Polytechnic University, Brooklyn, New York, and his BEEE from New York University, Bronx, New York. He is also chairman of the Educational Activities Committee for IEEE Long Island. His expertise is in analog with a diverse embedded processing education as it relates to analog design from his years at Burr-Brown and Texas Instruments. Steve was a circuit design engineer for his first 16 years in electronics. He then served as one of the first field application engineers with Burr-Brown Corp and also became one of their first global account managers, traveling to Europe, India and China.