Miniature MEMS-based speakers could revolutionize speech and music reproduction in mobile communication devices. They combine the advantages of a large frequency bandwidth and high acoustic quality with the ability to generate very high sound levels. Nevertheless, they are so tiny that they can be integrated into headphones. By Christoph Hammerschmidt @ eenewseurope.com
The breakthrough has now been achieved. The characteristics of the chip-based loudspeaker are impressive: With currently a area of 4×4 millimeters, the MEMS loudspeaker can be optimally integrated into headphones, hearables and hearing aids. They cover the entire frequency range from 20 Hz to 20 kHz as a one-way system – comparable HiFi loudspeakers typically consist of woofer, a midrange loudspeaker and a tweeter for the high frequencies. The tiny MEMS speakers achieve a sound pressure level of 110 dB for in-the-ear applications – this corresponds to the noise level of a jet aircraft at a distance of 100 meters.
California based company, Integrated Device Technology (IDT) has recently announced their new HS300x family of MEMS high-performance relative humidity (RH) and temperature sensors of dimension 3.0 × 2.41 × 0.8 mm DFN-style 6-pin LGA. Currently, there are four devices in this family—the HS3001, HS3002, HS3003, and HS3004. They are all the same from the view of functionality but differ slightly in terms of the accuracy of their relative humidity and temperature measurements.
The highlighted feature of this new lineup is that they do not require any user calibration. HS300x family of ICs has calibration and compensation logic integrated into the devices. These ICs output their fully corrected data using standard I2C protocols making the measured data from the sensors is rather easy.
As a side note, Relative humidity (RH) is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature. As the entire output consists of only four bytes of data, calculating the corresponding relative humidity in percent and temperature in degrees Celsius is very easy.
Although the HS300x sensors operate as slave devices on the I2C bus (supporting clock frequencies from 100 kHz to 400 kHz), only one HS300x IC can be connected directly to a single I2C bus. To connect multiple sensors to a single I2C bus, an I2C multiplexer/switch has to be used. It would have been easier if IDT had dedicated the unused pin as an optional I2C address input bit, which would allow two HS300x devices to be connected to a single I2C bus.
If you’re interested in testing these ICs prior to incorporating them into a design, SDAH01 or SDAH02 evaluation kit can come handy. Although both kits utilize the HS3001 sensor, the SDAH01 kit outputs the measured data to a PC while the SDAH02 displays the data on an LCD screen.
STMicroelectronics along with the audio company USound has created the first MEMS (Micro ElectroMechnical Systems) micro-loudspeaker based on semiconductors. It’s the smallest loudspeaker in the world, but it can produce a powerful noise. MEMS makes it possible. The speakers are being presented at CES 2018 in Las Vegas.
In the audio world, the electromechanical capabilities of MEMS have only been used to build tiny microphones. Speakers, on the other hand, still rely on traditional dynamic design principles. It has taken almost 150 years for semiconductor technology to replace Werner von Siemens’ superior loudspeaker principle in 1877 with something newer. The Coil-magnet combinations are still being used in smartphones, wearables, and headphones to produce sound.
We can understand the working principle of MEMS speaker very briefly here. At first, thin piezoelectric layers are applied to a semiconductor(Silicon). An electric signal is sent to the piezoelectric layer allowing the diaphragm connected to it vibrate. Eventually, the mechanical principle resembles that of a normal Coil-magnet loudspeaker. The sound is created by the vibration in the diaphragm. However, the magnet and coil are replaced by a piezo element. By applying this new technique, USound’s MEMS version appears to offer significant advantages when it comes to distortion and THD or Total Harmonic Distortion.
The MEMS loudspeaker developed by USound has dimensions of just 5 x 7 x 2 mm and has a frequency range of 2 to 15 kHz. It takes up half the space of its predecessors and needs only 20 percent of the energy that they do. The above figures are convincing enough for the speaker to be a perfect fit for mobile applications such as wearables and smartphones.
According to the manufacturer, these tiny speakers are the thinnest in the world. It has less than half the weight of a conventional Coil-magnet speaker. Most suitable applications include in many portable devices such as headphones, over-the-ear earphones, and more. With the help of this new speakers, augmented reality headsets or virtual reality systems can be more compact and comfortable. Innovative features also enable 3D sound production with striking accuracy. Its high efficiency reduces energy consumption and can easily be operated with much smaller and lightweight batteries. Higher efficiency results in less heat generated making systems operate cooler than ever before.
There’s a new addition to the Omron thermal sensor family. The D6T-1A-02 is the latest in sensory innovation with super-sensitive, infra-red (IR), non-contact temperature sensing capabilities using MEMS technology.
The Omron D6T thermal sensor is ideal for building automation applications, measuring the temperature in a room, or detecting occupancy, even when people are stationary. Additionally, because the D6T is fully non-contact it offers a wider detection range, as well as ultra-sensitive heat sensors – an excellent alternative to PIR detectors and pyroelectric sensors.
Making full use of MEMS technology, the D6T includes:
The ability to measure surface temps anywhere between -40° to 80°C (-40°-176°F) with an accuracy of +/- 1.5°C, and resolution of 0.06°.
A state-of-the-art MEMS thermopile, a sensor ASIC (Application Specific Integrated Circuit), and a signal processing microprocessor in a 12.0mm x 11.6mm x 9.2mm package.
A narrow field of view at 26.52, which allows for accurate readings of a specific object within range.
A joint research by the US Air Force Research Laboratory Sensors Directorate and Michigan State University have developed micro-electromechanical systems (MEMS) actuator based on smart materials, specifically vanadium dioxide (VO2). In the room temperature, Vanadium dioxide exhibits the Mott transition. It is a not-well-understood phenomenon known to occur in transition metal chalcogenides and transition metal oxides.
The research team was able to use VO2 thin films for making complex mirror support structures to create a programmable tilting mirror. Transition-metal oxides like VO2 require little energy to drive the transition and less than more conventional actuation technologies. This enables implementation of transition-metal oxide based MEMS in battery powered and mobile devices.
When an input voltage of 1.1V is applied, the mirror platform achieves the maximum vertical displacement of 75 microns. The average power consumption per mirror actuator is 6.5mW and the total power consumption is 26.1mW for the entire device. The Mott-MEMS actuator mirror showed vertical movements and tilt angles of 75 micrometers and 5.5 degrees, respectively.
While testing, vanadium dioxide (VO2) displayed hysteric behavior or memory effect. That means the current response to externally applied electrical force is dependent on the previous response. Such behavior will let the researchers predict its response nature for certain electrical signals and they can program the actuators to generate different types of responses.
Nelson Sepulveda, a professor of electrical and computer engineering at Michigan State University, said in a statement issued by Wright-Patterson Air Force Base,
The actuation of such devices using smart phase-change materials represents a new operating principle that enables their programming and reduces power consumption.
The study opened a new door in the development of MEMS mirror actuation technology, which could incorporate the use of the hysteresis of smart materials like VO2 for programming tilt angles and vertical displacements in MEMS mirrors. The researchers are focusing on developing programmable MEMs mirrors and improving the design to achieve more precise control and larger movements.
Thanks to Micro-Electro-Mechanical-Systems MEMS technology, which will be a 22-billion-dollar-worth industry by 2018, our mobile phones are equipped with accelerometers and gyroscopes so they know the direction and rotate our mobile screen as needed. The applications of MEMS had expanded a lot in various fields like: energy harvesting using piezoelectric effect, microphones, gyroscopes, pressure sensors, accelerometers and many more. Moreover, this micro-level technology is going to be nano-level with Nano-Electro-Mechanical-Systems NEMS.
The basic idea behind MEMS is about having moving parts inside the silicon chip. Accelerometers for example, one of the most famous applications of MEMS, sense the acceleration by measuring the change of the capacitance C1, C2 between a moving part/mass and fixed plates. So when acceleration is applied in a particular direction it can be detected and measured.
The amazing “How a smartphone knows up from down” video presented by Bill Hammack (engineerguy) can demonstrate in a clear way the principle of MEMS.
Last but not least, MEMS has applications in medical and health related technologies like Lab-On-Chip. LOCs can integrate a laboratory function in a single chip. So MEMS may not only solve technical problems, but they may also play an important role in solving problems in human health field.
Graham Prophet @ eedesignnewseurope.com discuss about two new MEMS accelerometers from Analog Devices:
Analog Devices (ADI) has added two devices to its low noise, low drift, low power, three-axis MEMS accelerometers. The low noise performance over high frequencies provided by the ADXL356 and ADXL357 MEMS accelerometers delivers high resolution vibration measurements that enable the early detection of machine failure in condition monitoring applications.
Accelerometers for vibration measurements & wireless condition monitoring – [Link]
The ADXL203 Module is high precision, low power, complete dual-axis accelerometers with signal conditioned voltage outputs, all on a single, monolithic IC. The ADXL203 measure acceleration with a full-scale range of ±1.7 g, ±5 g, or ±18 g. The ADXL203 can measure both dynamic acceleration (for example, vibration) and static acceleration (for example, gravity).The typical noise floor is 110 μg/√Hz, allowing signals below 1 mg (0.06° of inclination) to be resolved in tilt sensing applications using narrow bandwidths (<60 Hz).The user selects the bandwidth of the accelerometer using Capacitor CX and Capacitor CY at the XOUT and YOUT pins. Bandwidths of 0.5 Hz to 2.5 kHz can be selected to suit the application.
+/- 1.7g Dual-Axis IMEMS Accelerometer Using ADXL203 – [Link]
Graham Prophet discuss about a new 3 axis magnetic sensor @ edn-europe.com:
Memsic (Andover, Massachusetts) has added the MMC5883MA 3 axis magnetic sensor. The newest member of MEMSIC’s Anisotropic Magneto Resistive (AMR) based Magnetic Sensor family, it provides the industry’s highest accuracy, lowest noise and lowest power consumption, all combined in an industry standard small LGA package, and addresses demands of industrial and drone applications.
3-axis magnetic sensor claims highest sensitivity – [Link]
Three-axis MEMS accelerometers, Analog Devices’ ADXL354 and ADXL355 perform high-resolution vibration measurement to enable the early detection of structural defects via wireless sensor networks. The low power consumption of the devices lengthens battery life and reduces the time between battery changes. by Susan Nordyk @ edn.com
The analog-output ADXL354 and digital-output ADXL355 offer selectable measurement ranges of ±2 g to ±8 g and low 0-g offset drift. Both accelerometers provide guaranteed temperature stability with null offset coefficients of 0.15 mg/°C maximum. The ADXL354 boasts ultralow noise density (all axes) of 20 µg/√Hz and current consumption of just 150 µA in measurement mode. The ADXL355 has a noise density of 25 µg/√Hz and current consumption of 200 µA in measurement mode. Standby-mode current consumption is just 21 µA for each device.