by Steve Taranovich @ edn.com:
Gas sensing techniques are continually being investigated to improve selectivity and sensitivity of identifying different types of gases. There are resistive gas sensors, quartz crystal microbalance, direct thermoelectric, electrochemical cell and other exotic types such as MEMS-tunable Fabry-Perot filter spectral sensors with lead-selenide detector and pulsed broadband infrared emitter light source. The ams sensor is a resistive type.
The resistive sensor design relies upon heating circuitry for temperature control of the entire system. There are different types of resistive gas sensor techniques and construction. Some are based upon metal-oxide (MOX) thin films which are small in size, low-cost, and low power as well as able to use low-power integrated analog front ends.
ams develops MEMS VOC gas sensor – [Link]
by R. Colin Johnson @ eetimes.com:
The world’s first microelectromechanical system (MEMS) spectrometer on-a-chip was shown today at at Photonics West (San Francisco, February 10-12) by Si-Ware Systems (SWS, Cairo, Egypt with offices in La Canada, Calif.) Instead of transporting materials across sometimes great distances to be analyzed with a normal bench-top spectrometer, Si-Ware’s MEMS-powered spectrometer fits in the palm of your hand and thus can be taken to the material to be analyzed.
“Spectrometers are usually bench sized, so your have to take the object to the bench, but now with our MEMS sized you can can take the spectrometer to the object,” said executive vice president, worldwide marketing and business development of Si-Ware, Scott Smyser.
World’s 1st Spectrometer On-a-Chip – [Link]
MEMS manufacturer Kionix Inc recently announced the introduction of their thinnest full-functional tri-axis accelerometers: the KX112 (2.0 x 2.0 x 0.6 mm) and the KXCJB (3.0 x 3.0 x 0.45 mm). At 0.45 mm thick the KXCJB is half the thickness of its predecessor.
The size of the KX112 makes it suitable for integration into compact devices for wearable and health/medical applications. A wide range of functionality is built into the small outline with algorithms to detect motion for power management, free-fall detect for device protection or warranty monitoring, an orientation engine for portrait/landscape detection and tap/double-tap for user interface functionality. It also incorporates Kionix’s FlexSet performance optimizing technology for control of accelerometer power usage and noise value trade-off. It features a large 2048-byte FIFO/LIFO buffer which allows the rest of the system to remain in low power mode while the KX112 stores sensor measurements. The accelerometer can supply output data with 8 or 16-bit resolution and with a user selectable range of ± 2g, 4g or 8g.
Tri-axis Accelerometers get Thinner – [Link]
by Steve Taranovich @ edn.com:
The BME680 from Bosch Sensortec is the world’s first environmental sensor combining pressure, humidity, temperature, and indoor air quality in a single 3×3mm2 package.
The new IC enables mobile devices and wearables to monitor indoor air quality measurement in a low power, small footprint package. The level of integration is what makes this solution so attractive as well as Bosch’s capabilities with software algorithms for a full solution.
The IC will enable multiple new capabilities for portable and mobile devices such as air quality measurement, personalized weather stations, indoor navigation, fitness monitoring, home automation, and other applications for the Internet of Things (IoT).
Combo MEMS sensor solution with integrated gas sensor – [Link]
A simplified explanation of how a capacitive MEMS accelerometer works.
How an accelerometer works! – [Link]
by Bill Schweber @ digikey.com:
With very few exceptions, every electronic circuit needs an oscillator, also referred to as a clock, clock generator, or timing circuit. Its role is to provide the “heartbeat” for the processor, memory functions, communications ports, A/D and D/A converters (if any) and many other functions. In non-critical, low-budget situations such as $10 mass-market electronic thermometers, this clock may be made from a simple resistor/capacitor (RC) oscillator. However, for the vast majority of situations which are more critical, the oscillator is based on a quartz crystal (Figure 1). This is a mature (80+ years) and highly effective technology which can support of wide range of frequencies from kHz to hundreds of MHz, with performance spanning fairly good to excellent, depending on the crystal cut, fabrication, packaging, and other considerations.
MEMS Oscillators Challenge Quartz Crystals in RF Applications – [Link]
by Graham Prophet @ edn.com:
STMicroelectronics’ MP23AB02B MEMS microphone maintains ultra-low distortion at less than 10% up to very high external sound-pressure levels, enabling equipment such as smartphones and wearable devices to perform better when placing calls or recording audio in loud environments.
With acoustic overload level of 125 dB SPL and signal-to-noise ratio of 64 dBA, the 3.35 x 2.5 x 0.98-mm microphone employes ST’s dedicated preamplifier design, which prevents saturation of the output signal even when background-noise levels are high, such as in concert venues, bars or clubs, or if the user is speaking loudly close to the microphone. In addition, omnidirectional sensitivity ensures overall performance and versatility in mobile applications.
Smart MEMS mic hears better in loud environments – [Link]
SiTime SiT8008 is a programmable MEMS oscillator reaching quartz precision but with higher reliability and lower g-sensitivity. Also SiTime is one of companies who received investments from Rosnano – Russian high-tech investment fund.
The trick is that to reach maximum Q-factor (up to ~186’000 according to patents) MEMS resonator must operate in vacuum. So they package resonator _inside_ the die in hydrogen atmosphere, then anneal it in vacuum so that hydrogen escapes through silicon. So we see here only a cap with contacts to “buried” MEMS resonator. We were unable to reach the resonator itself without x-ray camera or ion mill.
SiTime SiT8008 – MEMS oscillator : die-shot – [Link]
by Steve Taranovich:
I recently spoke to Piyush Sevalia, Executive Vice President, Marketing at SiTime Corporation,about their newly introduced 32 kHz TCXO (temperature compensated oscillator) which they claim to be the smallest, lowest power device in the industry. With its tiny footprint and ultra-low power consumption, the SiT1552 MEMS TCXO decreases the size and increases battery life of wearable electronics and Internet of Things (IoT); such benefits are not achievable from legacy quartz devices.
SiTime enters wearables, IoT markets with 32 kHz MEMS TCXO – [Link]