Mechanical-Systems (MEMS) is the integration of mechanical elements (levers, springs, deformable membranes, vibrating structures, etc.), sensors, actuators, and electronics (resistors, capacitors, inductors, etc.) on a common silicon substrate through microfabrication technology. MEMS devices are today considered as one among the most promising technologies of this century, capable to revolutionize the industrial world and the commercial product market. Micro-Electro- MEMS can be considered as “intelligent” systems which combine mechanical and electronic functions in extremely reduced dimension. The dimension of a MEMS device is in the order of the microns and it is manufactured directly on a silicon wafer.
MEMS devices are designed to work in concert to sense and report on the physical properties of their immediate or local environment, or, when signaled to do so, to perform some kind of controlled physical interaction or actuation with their immediate or local environment.
The advanced device and process concepts thrust enables the integration and co-location of actuators, sensors, electronics, and power supplies to merge the functions of compute, communicate and power together with sense, actuate and control to change completely the way people and machines interact with the physical world. Some well-known examples of MEMS-enabled functionality in everyday life are airbag deployment in automobiles; motion and orientation detection in smartphones; and blood pressure measurement in IV lines and catheters.
Using an ever-expanding set of fabrication processes and materials, MEMS will provide the advantages of small size, low-power, low-mass, low-cost and high-functionality to integrated electromechanical systems both on the micro as well as on the macro scales. Further, demands for increased performance, reliability, robustness, lifetime, maintainability and capability of military equipment of all kinds can be met by the integration of MEMS into macro devices and systems.
Analyst firm Yole Développement expects the global market for MEMS and sensors to double in the next five years, reaching $100B by 2023, spurred by growth of autonomous mobility products such as Internet of Things (IoT) devices, autonomous cars, fitness and healthcare wearables, and agricultural sensors.
The list of amazing new products incorporating MEMS and sensor devices is growing rapidly. Applications are wide and varied—from beds that monitor heart rates and breathing, to agricultural devices that measure sunlight, soil pH, and moisture content, to products aimed at enhancing athletic performance. The list goes on and on, growing daily with nearly limitless potential
Advancements in MEMS technology such as sensor fusion led to high usage in various industrial verticals such as automotive, healthcare, aviation and consumer electronics.
Some of device concepts include: the integration of micro devices with communication, control, computation and power components, miniature electromechanical signal processing elements (tuning elements, antennas, filters, mixers), miniature optoelectromechanical devices (cross-bar switches, fiber-optic interconnects and aligners, deformable gratings, and tunable interferometers), force/motion balanced accelerometers and pressure sensors, atomic-resolution data storage, electromechanical signal processing, process control (HV AC equipment, mass flow controllers), simultaneous, multi-parameter sensing with monolithic sensor clusters, and biochemical identification and manipulation
In the automotive sector, where more and more sensors are being integrated into both conventional and self-driving vehicles, demand for MEMS-based technology is also high. Micro Electro-Mechanical Systems (MEMS) accelerometer devices have became commercial products for large-volume and large-scale applications such as: airbag crash sensing, inertial measurement and navigation, vibration monitoring of machines and structures, and also for earthquake monitoring. In automotive industry, this technology is widely implemented in the airbag systems pertaining to rising passenger safety concerns coupled with favourable government regulations further contributing to the smart sensors market growth.
The healthcare sector, where a growing number of handheld medical devices are being used to diagnose and monitor patients, is also helping to drive growth in the MEMS market. Rising adoption of wearable technology such as smart watches and wrist bands is expected to surge the demand for MEMS technology in the smart sensor market.
On the gaming front, for example, AdHawk Microsystems recently developed a tiny chip with low cost, and minimal power consumption, that is expected to “revolutionize the next generation of VR/AR headsets. Currently, bulky camera-based sensors make AR/VR products heavy and oversized, the publication reports, while AdHawk’s eye-tracking sensors are created from MEMS. “Previous eye-tracking systems have had to rely on cameras tethered to a computer. In contrast, the AdHawk system is embedded in AR/VR headsets or glasses and captures thousands of data points per second.”
Miniaturised MEMS sensors have become popular for military applications. These sensors could be deployed in airports, military camps, public buildings and other strategic locations. For example, MEMS pressure sensors are used in aircraft, jets, helicopters and various harsh environments; chemical sensors are used to provide accurate and timely information to the soldiers regarding noxious battlefield chemicals; friend-or-foe-identification devices enable soldiers to more easily distinguish their own forces from the enemy’s.
Eric Mounier, a featured speaker at SEMI-MSIG European MEMS & Sensors Summit, has identified three distinct eras in MEMS’ evolution:
- The “detection era” in the very first years, when we used simple sensors to detect a shock.
- The “measuring era” when sensors could not only sense and detect but also measure (e.g., a rotation).
- The “global-perception awareness era” when we increasingly use sensors to map the environment. We conduct 3D imaging with Lidar for autonomous vehicles. We monitor air quality using environmental sensors. We recognize gestures using accelerometers and/or ultrasonics. We implement biometry with fingerprint and facial recognition sensors. This is possible thanks to sensor fusion of multiple parameters, together with artificial intelligence.
Numerous technological breakthroughs are responsible for this steady stream of advancements: new sensor design, new processes and materials, new integration approaches, new packaging, sensor fusion, and new detection principles.
MEMS and sensors are entering a new and exciting phase of evolution as they transcend human perception, progressing toward ultrasonic, infrared and hyperspectral sensing.
The rising applications of MEMS and sensors into vast array of connected devices, is also raising cyber security risks. MITRE cybersecurity expert Cynthia Wright opened MSEC 2018 with a keynote on cybersecurity, “From the destruction of critical infrastructure, cyberattacks on life-critical medical devices such as insulin pumps and heart monitors, and intrusions on autonomous vehicle safety systems, MEMS and sensors suppliers have a responsibility to help improve cybersecurity of connected devices,” she added.
Allaying the potential fears of a roomful of suppliers envisioning complete redesigns of their products, Wright said that not every device requires the same level of security, and suppliers can make a difference with even “minor tweaks.”
The future is the point when sensors can mimic or augment most of our perception: vision, hearing, touch, smell and even emotion/empathy as well as some aesthetic senses. “The era of global awareness sensing is upon us. We can either view global awareness as an extension of human sensing capabilities (e.g., adding infrared imaging to visible) or as beyond-human sensing capabilities (e.g., machines with superior environmental perception, such as Lidar in a robotic vehicle),” writes Eric.
The enhanced perception will also allow robots to help us in our daily lives (through smart transportation, better medical care, contextually aware environments and more). We need to couple smart sensors’ development with AI to further enhance our experiences with the people, places and things in our lives.
Future marrying AI with MEMS
In order to achieve the edge computing that people talk about in a host of applications including 5G networks and the Internet of Things (IoT), you need to pack a lot of processing power into comparatively small devices.
Researchers at the Université de Sherbrooke in Québec, Canada, have managed to equip a microelectromechanical system (MEMS) device with a form of artificial intelligence, marking the first time that any type of AI has been included in a MEMS device. The result is a kind of neuromorphic computing that operates like the human brain but in a microscale device. The combination makes it possible to process data on the device itself, thus improving the prospects for edge computing.
The AI method the researchers demonstrated in their research, which is described in the Journal of Applied Physics, is something called “reservoir computing.” Reservoir computing is most often used on inputs that depend on time (as opposed to inputs such as images, which are static). So reservoir computing uses a dynamical system driven by the time-dependent input. The dynamical system is chosen to be relatively complex, so its response to the input can be fairly different from the input itself.
The special trick used by reservoir computing is to combine all the dimensions linearly to get an output that corresponds to what we want the computer to give as an answer for a given input,” said Sylvestre. “That’s what we call ‘training’ the reservoir computing. The linear combination is very simple to compute, unlike other approaches to AI, where one would attempt to modify the inner working of the dynamical system to get the desired output.”
In most reservoir computing systems, the dynamical system is the software. In this work, the dynamical system is the MEMS device itself. To achieve this dynamical system, the device uses the nonlinear dynamics of how a very thin silicon beam oscillates in space. These oscillations create a kind of neural network that transforms the input signal into the higher dimensional space required for neural network computing.
Sylvestre explained that it’s hard to modify the inner workings of a MEMS device, but it’s not necessary in reservoir computing, which is why they used this approach to do AI in MEMS. “Our work shows that it’s possible to use the nonlinear resources in MEMS to do AI,” said Sylvestre. “It’s a novel way to build ‘artificially smart’ devices that can be really small and efficient.”
A possible application for this AI-equipped MEMS could be an accelerometer MEMS in which all the data the device is collecting is processed within the device without the need for sending that data back to a computer, according to Sylvestre.
While the researchers have not yet focused on how they would power these MEMS, it’s assumed that the devices’ miserly power use would allow them to run on only energy harvesters without the need for batteries. With that in mind, the researchers are looking to apply their AI MEMS approach to applications in sensing and robot control.
MEMS market will experience a 17.5% growth in value between 2018 and 2023, to reach US$ 31 billion at the end of the period,” reported Dr. Eric Mounier, Principal Analyst, MEMS & Photonics, at Yole Développement (Yole). “The consumer market segment is showing the biggest share, with more than 50% . The good news is that almost all MEMS devices will contribute to this growth.” MEMS market segments including inertial, optical MEMS, microfluidics, and new micro components.
Amongst the numerous existing MEMS devices, inkjet heads will grow, with the consumer market representing more than 70% of printhead market demand.
However, the RF industry is still playing a key role in the MEMS industry development. Excluding RF, the MEMS market will grow at 9% over 2018 – 2023. With RF MEMS devices, CAGR reaches 17.5% during the same period. Driven by the complexities associated with the move to 5G and the higher number of bands it brings, there is an increasing demand for RF filters in 4G/5G, making RF MEMS (mainly BAW filters) the largest-growing MEMS segment.
Numerous pressure sensor applications also contribute to market expansion. In automotive, pressure sensors have the highest number of applications, with many advantages such resistance to toxic exhaust gas and harsh environments, higher accuracy, and the development of intelligent tires that deliver more information on tire status (especially for future autonomous cars).
For consumer, mobiles and smartphones still account for 90% of pressure sensor sales, and cost reduction is the priority vs. size reduction because size is already very small. Although there are no big “killer” applications expected in the future, new applications are emerging: smart homes, electronic cigarette, drones, and wearables.
Then after, are coming the MEMS microphones. “In the range of US$105 million in 2008, the MEMS microphone market was worth US$402 million in 2012 and reached the US$1 billion milestone in 2016”, asserts Guillaume Girardin, Director of the Photonics, Sensing and Display division at Yole. “Currently, almost 4.5 billion units are shipped annually. The main application is mobile phones, which comprise 85% of shipment volumes, in a consumer market that makes up 98% of the total shipment volume. Tablets and PCs/laptops take second and third place, with 5% and 3.2% of total shipment volumes, respectively.”
The uncooled IR imager market keeps growing due to a continuous price decrease over the last few years stemming from new technologies such as WLP and silicon lenses, as well as increasing acceptance from customers.
In 2017, the biggest surprise was Broadcom becoming the #1 MEMS player. Established players like Robert Bosch, STMicroelectronics and HP also performed well. Other MEMS players posting significant growth are: FormFactor, benefiting from the semiconductor business’s excellent health; and ULIS, with uncooled IR imaging still growing annually into multiple applications including consumer – thermography, firefighting, night vision, smartphones, drones, and military.
Global Smart Sensor Market is anticipated to grow at a CAGR of over 17% to reach USD 80 billion by 2024. Advancements in consumer electronics coupled with favourable government initiatives is anticipated to drive the smart sensors industry growth over the forecast timeline.