Thin-film PMUTs: a review of over 40 years of research

Abstract

Thin-film PMUTs have been important research topics among microultrasound experts, and a concise review on their research progress is reported herein. Through rigorous surveying, scrutinization, and perception, it has been determined that the work in this field began nearly 44 years ago with the primitive development of functional piezoelectric thin-film materials. To date, there are three major companies commercializing thin-film PMUTs on a bulk scale. This commercialization illustrates the extensive contributions made by more than 70 different centers, research institutes, and agencies across 4 different continents regarding the vast development of these devices’ design, manufacturing, and function. This review covers these important contributions in a short yet comprehensive manner; in particular, this paper educates readers about the global PMUT outlook, their governing design principles, their manufacturing methods, nonconventional yet useful PMUT designs, and category-wise applications. Crucial comparison charts of thin-film piezoelectric material used in PMUTs, and their categorically targeted applications are depicted and discussed to enlighten any MEMS designer who plans to work with PMUTs. Moreover, each relevant section features clear future predictions based on the author’s past knowledge and expertise in this field of research and on the findings of a careful literature survey. In short, this review is a one-stop time-efficient guide for anyone interested in learning about these small devices.

Development of a Small-Footprint 50 MHz Linear Array: Fabrication and Micro-Ultrasound Imaging Demonstration

“…The method presented here allows a more compact integration of the array and interconnect compared to the cumbersome bending of the FPCB toward the back or side of the array, as implemented in previous work [ 22 , 23 , 24 , 25 , 26 ]. Vacuum-deposited metals are widely used as electrodes in piezoceramic and MUT transducers [ 17 , 20 ]. Laser micromachining has also been used to pattern element electrodes on piezoceramic substrates [ 41 , 42 ].…”

“…Capacitive and piezoelectric micromachined ultrasound transducers (MUTs) can be fabricated at a large scale and can be closely integrated with transmit and receive electronics to achieve small-footprint transducers [ 16 , 17 , 18 ]. However, there are limited MUTs that operate at high frequencies (>20 MHz) [ 19 , 20 ].…”

Advances and Applications of Metal‐Organic Frameworks (MOFs) in Emerging Technologies: A Comprehensive Review

“…MEMS finds applications in a broad range of areas, such as medical technology, [ 214 , 215 , 216 ] telecommunications, [ 217 ] consumer electronics, [ 218 ] and automotive systems. [ 219 ] Innovations like inertial measurement units [ 220 ] in smartphones, pressure sensors [ 221 ] in cars, micro‐mirrors [ 222 ] in projection systems, and MUTs [ 223 , 224 , 225 , 226 , 227 , 228 , 229 , 230 , 231 , 232 ] as fingerprint sensors/medical imaging systems all demonstrate the transformative power of MEMS technology.…”

Ultra-compact and high-performance suspended aluminum scandium nitride Lamb wave humidity sensor with a graphene oxide layer

“…Microelectromechanical Systems (MEMS) technology based solutions are getting more and more attention due to their high-performance, low-cost, and compact-size. [24][25][26][27][28] In recent years, piezoelectric surface acoustic wave (SAW) technology with a humidity sensing layer has gained widespread adoption, owing to its simplified fabrication process. [29][30][31] However, the ongoing miniaturization trend in wireless devices necessitates the development of smaller sensors.…”