“MEMS-based miniaturization enables low-cost, distributed sensing at scale”

As devices become smaller, smarter and more complex, sensor technology increasingly determines system performance and reliability. MEMS play an important but often underestimated role in this shift. For engineers, a solid insight into MEMS is essential for the design, integration and adaptation of future systems.

Micro-electromechanical systems (MEMS) quietly power the devices we use every day, from smartphones to cars and medical systems. MEMS play an important role in applications where standard, off-the-shelf sensors are insufficient. Michael Kraft, professor at KU Leuven, points to medical applications such as piezoelectric micromachined ultrasound transducers (PMUTs), which replace bulky, high-voltage ultrasound transducers with MEMS-based arrays of microscopic piezoelectric membranes. This approach potentially enables handheld ultrasound devices.

Kraft also highlights neural technologies, including implantable electrode arrays designed to interface with the brain: “There are currently clinical trials ongoing aimed at stimulating the visual cortex in blind people. I wouldn’t say vision can be fully restored for these patients, but thanks to MEMS, they can be given a perception of vision again.”

Trained as an electrical engineer, Kraft has worked at leading universities, including those of Southampton and Liege in Europe and Berkeley in the US. He’s been active in MEMS since the late 1990s. In Leuven, he currently leads micro- and nanosystems research, runs the university cleanroom and works hands-on with teams developing and fabricating MEMS devices in close collaboration with industrial partners.

Tailored training

“A MEMS sensor is essentially a transducer,” Kraft explains. “It converts a physical input into an electrical signal. While the underlying physics can be complex, the basic principle is often surprisingly intuitive.”

For example, inside the sensor of a MEMS-based accelerometer, a tiny mass is suspended by microscopic springs within a silicon structure. When the device accelerates, the mass moves slightly. This changes the electrical property between electrodes. The resulting electrical signal is then processed by an IC. Although the movement involved may be only a few picometers, smaller than a single atom, the effect is measurable and repeatable. This is what allows a smartphone to detect orientation changes or a vehicle to sense rapid deceleration in an airbag system.

Importantly, the visible chip is only part of the system. A complete MEMS device integrates the mechanical sensor element, electronic readout circuitry (ASIC), electrical interconnects and protective packaging. Together, these form a miniature system that bridges the physical and digital worlds.

The tiny scale that makes MEMS so powerful also makes them difficult to design. A pressure sensor membrane may deflect only a few picometers in response to a meaningful signal. With technology this small, tiny variations in geometry, material properties or manufacturing processes can significantly affect performance.

Kraft offers a three-day introductory course on MEMS through High Tech Institute. This training covers the general aspects of the technology before moving into transduction principles for physical sensors. “Think accelerometers, gyroscopes, pressure sensors, resonant type sensors.” According to Kraft, the course is great for people who are just getting into MEMS or are looking for a refresher of the fundamentals.

Alongside this foundation, a second training for more experienced participants is available on request. This course is tailored to the maturity and interests of the participants and can focus on selected topics, including but not limited to piezoelectric devices, inertial sensors, resonant sensing, state-of-the-art technology and emerging design approaches.

MEMS innovation

Looking ahead, Kraft sees strong growth, driven by data-intensive technologies such as AI and robotics, where small, low-power, scalable sensors are essential. “Sensors detect unbiased, real-world data. MEMS devices are well-suited for this purpose because they’re small, low-power and scalable.”

Another emerging domain identified by Kraft is infrasound, which refers to sound waves well below 20 hertz. Here, the applications range from early warning systems for earthquakes and volcanoes to security monitoring. Today’s infrasound sensors are bulky and expensive, but MEMS-based miniaturization could enable low-cost, distributed sensing at scale.

“Maintaining Europe’s strong position in MEMS,” Kraft argues, “requires continued investment and training.” His courses at High Tech Institute, sitting at the forefront of the current MEMS technology, help engineers and companies build the knowledge needed to translate emerging ideas into practical, competitive sensor solutions while strengthening Europe’s long-term expertise in the field.

This article is written by Marleen Dolman, freelancer for High Tech Systems.