Dear Colleagues,

Micromechanical actuators and sensors are essential parts of micro-electro-mechanical systems (MEMS). During the last three decades, they have benefited from the significant technological progress in microelectronics and microsystem technology. Besides the physical transducer principles (e.g. electrostatic, piezoelectric…) the MEMS devices can be differentiated according to their technology in bulk- and surface micro-machined devices commonly using crystalline silicon or thin film materials (e.g., poly-Si, TiAl-alloys…). Due to miniaturization and cost reduction, MEMS sensors (e.g., for yaw rate and acceleration) are indispensable components of everyday life (e.g., present in every smartphone or automobile). For MEMS actuators also high positioning speed, low power consumption, friction-free operation, and high reliability can be achieved. By combining actuator mechanisms, sensors for position feedback and microelectronic circuitry complete highly miniaturized servomechanism and mechatronic systems can be realized on the same chip at a low cost.

An increasing number of applications have been emerged for MEMS actuators and sensors. Practical examples are electrostatic MOEMS for optical applications, such as micro scanning mirrors with on-chip integrated position sensors, presently used in solid-state LIDAR systems for autonomous navigation, spectral tunable QCL-laser sources or highly miniaturized NIR spectrometers. Electrostatic out-of-plane comb drive MEMS actuators are now state of the art.

But we also consider completely new developments: For instance, CMOS-compatible piezoelectric actuators (e.g. based on AlNi or AlScNi) are highly attractive when lower driving voltages and power consumption are required for mobile systems, e.g. AR displays. CMUT and PMUT devices (capacitive and piezoelectric micro-machined ultrasonic transducer) can be used simultaneously for generation and sensing of ultrasonic waves and for fully integrated phased arrays needed for IoT-applications (e.g. for real-time machine diagnostics) or medical applications. Fluidic MEMS actuators and bio-chemical sensors are developed for pumps and valves of medical drug delivery, micro-reactors and lab-on-chip systems. Significant in-plane deflections can be realized by means of a novel class of electrostatic NED actuators, which are considered interesting for future use in acoustic (loudspeaker) or microfluidic (micro pump) applications. Due to low-damping of non-fluidic MEMS actuators, a sophisticated closed-loop position control is essential for practical applications. Although silicon is the dominant material in this field, other materials are also of interest in terms of novel MEMS actuators, such as smart hydrogels or shape memory alloys.

The objective of this Special Issue is to present actual and significant work in the field of MEMS actuators and sensors. Authors from academia and industry are kindly invited to share their research innovations in this field. We particularly welcome review articles and original research papers aiming to the related key issues of basic research, device and technology development, system integration, and practical application of MEMS actuators and sensors, with a special focus on combined MEMS actuator sensor systems.

This Special Issue invites but is not limited to contributions in the following topics:

• Novel MEMS device concepts, sensor and actuation principles of transducers and micro actuators, e.g., electrostatic, electromagnetic, piezo-electric, thermal, pneumatic, levitation;
• MEMS design, modeling and simulation of coupled fields and multi-physical domains;
• Advanced simulation techniques and tools for MEMS (ROM, coupled simulation);
• Closed-loop control and sensing of resonant and non-resonant MEMS driving;
• Optical MEMS, e.g., micro scanning mirrors, spatial light modulators, Fabry–Perot filters;
• CMUT and PMUT devices (capacitive and piezoelectric MEMS ultrasonic transducer);
• Acoustical MEMS, e.g., MEMS loudspeakers based on NED actuation;
• MEMS for fluidic and pneumatic MEMS, e.g., micro-valves and pumps, ink print heads;
• Novel materials and MEMS fabrication technologies for micro-actuators and sensors, e.g., CMOS-compatible piezoelectric MEMS based on AlNi, AlSrNi or other novel materials, smart hydrogel sensors and actuators, shape memory alloy-based micro-actuators;
• Results on calibration strategies, reliability and long-term stability of MEMS devices;
• Practical application of micro-actuators and sensors, e.g., MOEMS-based solid-state LiDAR used for autonomous driving, tunable lasers, miniaturized NIR spectrometer, CMUT and PMUT array devices for IoT- and medical applications, fluidic MEMS actuators and bio-chemical sensors for biomedical applications in diagnostics, lab-on-chip and micro-reactors;
• Review articles on MEMS-actuators and sensors, their technology progress, and application landscape.

You may choose our Joint Special Issue in Actuators.

Dr. Thilo Sandner
Prof. Dr. Gerald Gerlach
Prof. Dr. Jan Mehner
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• micro-mechanical actuator
• MEMS
• MOEMS
• micro-mirror
• spatial light modulator
• micro scanning mirror
• resonant and non-resonant MEMS driving control
• acoustical MEMS
• microfluidic and hydraulic micro-actuators
• CMOS compatible MEMS actuators