Microfine Materials Technologies

Launched in the early 2000s as an offshoot from the National University of Singapore (NUS), Microfine Materials Technologies (MMT) has established itself as a harbinger of innovation in advanced piezoelectric materials and high-performance devices.

MMT’s foundations are deeply embedded in the research conducted by NUS’s Mechanical Engineering Department on lead-zinc-niobate-lead-titanate (PZN-PT) solid solution single crystals. The firm has adeptly capitalized on this foundational knowledge to trailblaze advancements in the piezoelectric material and device technology sectors. MMT’s notable contributions, such as the development of compact low-frequency underwater transducers of superior performance, high-sensitivity accelerometers, and acoustic vector sensors, underscore its dedication to expanding the technological envelope, especially in underwater applications.

This venture’s early stages were significantly bolstered by the support of the Agency for Science, Technology, and Research (A*STAR), previously known as the National Science and Technology Board, along with the Future Systems and Technology Directorate/DSO National Laboratories. Under the proficient leadership of CEO Dr. Leong-Chew Lim, MMT has evolved into a paragon of resilience, groundbreaking innovation, and an unwavering commitment to pushing the boundaries of piezoelectric technology.

Throughout its history, MMT has focused on developing key technologies that can revolutionize the current technological paradigm. One of its noteworthy achievements is the successful growth of large-size high-quality PZN-PT solid solution piezoelectric single crystals. These crystals, emblematic of MMT’s relentless pursuit of excellence, have piezoelectric coefficients that far exceed those of conventional piezoceramic materials. This breakthrough heralds new opportunities to create high-performance devices, marking MMT’s indelible impact on the technological landscape. MMT, guided by a vision to convert theoretical insights and new design concepts into leading-edge, practical solutions, has consistently maintained its position at the vanguard of industry innovation.

“The broadband characteristic of single crystals is especially advantageous for underwater sound transmission and reception in imaging systems, while the compact and power efficient nature of the resultant transducers will help propel the various unmanned platforms not possible with current sonar technology,” adds Dr. Leong-Chew Lim.

Growth Of Pzn-Pt Single Crystals

For over two decades, scientists worldwide faced the challenge of advancing PZN-PT piezoelectric single crystals, formally known as lead-zinc-niobate-lead-titanate, due to their complex growth process. However, MMT demonstrated unparalleled perseverance and innovation by creating a proprietary technique to cultivate large-scale, compositionally uniform PZN-PT single crystals that exceed 30 mm in edge length. This groundbreaking development became commercially viable and received accolades from IEEE’s Piezo Single Crystal Standards, thereby redefining industry standards.

Compared with lead-magnesium-niobate-lead-titanate (PMN-PT) and lead-indium-niobate-lead-magnesium-niobate-lead-titanate (PIN-PMN-PT) single crystals, two other commercially available piezoelectric single crystals, PZN-PT single crystal is distinguished by their exceptional piezoelectric coefficients of up to 3000 pC/N and high electromechanical coupling factors which exceed 90 percent typically. Such high performance results in a significant enhancement in voltage response and bandwidth for devices incorporating these materials. MMT’s dedication to advancing piezoelectric technology is further demonstrated in its focus on the transverse 32-mode piezoelectric coefficient. This particular activation mode has laid the foundation for the next generation of underwater transducers, heralding a new era in underwater communication, imaging, and target classification technologies.

Redefining Underwater Exploration

Microfine Materials Technologies (MMT) epitomizes innovation in underwater technology with the introduction of transducers that redefine industry benchmarks. These advanced transducers have significant advantages over traditional models, including minimized dimensions, augmented bandwidth, and superior voltage response and/or sensitivity. Notably, MMT’s low-to-mid frequency single-crystal-based transducers exhibit relative bandwidths of up to 60 percent. This compares favorably to current piezoceraimc-based variants which demonstrate a relative bandwidth of only 15- 25 percent.

A hallmark of MMT’s technology is the integration of 32-mode PZN-PT single crystals into a uniquely designed square-pipe-like hollow motor section for reduced crystal volume while maintaining desirable acoustic characteristics.

Together with a low acoustic impedance of just four to six times greater than water, this allows for the development of compact broadband underwater transducers that are acoustically matched with water. No pre-stress mechanism is required in such a design due to the extremely light head mass used, being less than 0.5g typically. This breakthrough challenges traditional paradigms, enabling the production of transducers with much reduced physical footprints and the ability to design and fabricate high-density sonar transmitter arrays of low to mid frequencies not possible for the first time.

MMT’s transducers and arrays made from PZN-PT single crystals are highly tunable and energy efficient, offering versatile acoustic configurations tailored to varied operational requirements. These transducers are capable of multi-band operation, a feature unattainable with current transducer technologies, illustrating MMT’s prowess in advancing sonar technology.

The introduction of MMT’s transducers represents a significant leap in underwater technology. These innovations improve the quality of data transmission and imaging resolution and minimize false alarms, establishing a new underwater exploration and research standard.

Multi-Band High-Density Array And Low-Frequency Parametric Array Possibilities

MMT has pioneered the development of compact, acoustically matched, broadband underwater transducers (WIPO/PCT International Publication No. WO 2023/182925A1), setting a new standard in sonar technology. These transducers are designed with significantly reduced footprints, making it possible to create high-density sonar projector arrays with more transducer elements. This design innovation challenges traditional approaches and enhances sonar systems’ capability and flexibility.

The above-said high-density array concept allows for various acoustic configurations and supports multi-band operations that were previously unattainable with existing technologies. Also, by embedding the high-frequency transmitter arrays within the space among the low-footprint low-frequency elements, slim and thin dual- and triple-frequency synthetic aperture sonar (SAS) transmitter arrays can be constructed, marking a significant leap in the versatility and efficiency of underwater acoustic technology notably in the field of underwater exploration and mapping.

Further exemplifying MMT’s innovative edge is the possible development of a compact low-frequency parametric array. This breakthrough is achievable by using a high-density, high-source-level array of small-footprint, acoustically-matched projector elements as the primary sources and by maintaining the frequencies and the drop-down ratio (DDR) at low levels—say, below 20 kHz and 5, respectively. According to established theoretical studies, such conditions could increase power efficiency by 20x to 40x. Furthermore, the resulting difference-frequency beam, of a few kHz in frequency, would exhibit a nearly parallel beam pattern with reduced spreading and absorption losses. Such a low-frequency parametric array is expected to display a longer detection range and much-reduced reverberation not possible with present-day technologies. For this particular application, the small-footprint elements should be designed for a high source level instead to keep the array size small.

A Holistic Approach To Transducer Technology

MMT has diversified its product lineup to cater to cost-sensitive and high-performance market segments within underwater acoustic technology. In this regard, the company has developed 33 piezoceramic-driven piston-type low-frequency transducers for budget-conscious applications, which are designed to operate within the central frequency range of 20 to 40 kHz. These projectors are characterized by a modest relative bandwidth of 15 to 25 percent and are noted for their larger size and greater weight compared to their high-end counterparts.

In contrast, MMT’s single-crystal projectors are engineered for premium applications and are particularly effective in the sub-50 kHz frequency range. These projectors outperform piezoceramic alternatives in terms of acoustic properties and sizes, making them ideal for demanding applications notably on small platforms like unmanned underwater or air vehicles.

MMT uses transducers made from piezo-composite active materials for scenarios requiring high-frequency operation. These devices are designed for central frequencies ranging from 100 to 300 kHz, incorporating various broadband designs to meet the needs of advanced sonar systems. This strategic product differentiation enables MMT to address a broad spectrum of market demands, from cost-effective solutions to cutting-edge performance requirements in underwater acoustics. ( see Table 1 )

As MMT stands at the forefront of innovation, these advancements redefine expectations in underwater exploration. The journey goes beyond incremental improvements; it is a pioneering effort to reshape sonar technology, enhance capabilities, and push the boundaries of what underwater systems can achieve. The compact, acoustically matched broadband transducers, along with individual transducers and high-density sonar projector arrays, set unprecedented standards in performance and efficiency, ushering in a new era of underwater technology.

MMT’s Diverse Portfolio Beyond Underwater Transducers

Beyond its advancements in underwater transducer technology, MMT proudly presents a range of pioneering innovations that redefine the limits of sensor and actuator technologies.

MMT presents a comprehensive suite of high-sensitivity miniature hydrophones for various applications, meeting both budget-conscious and performance-driven requirements. The lineup includes cost-effective piezoceramic hydrophones and superior ultra-high sensitivity single-crystal hydrophones with off-resonance sensitivities surpassing –193 decibels (dB). Besides, MMT has developed innovative compact vector hydrophones and single-crystal accelerometer-based acoustic vector sensors. The firm’s hydrophones and directional underwater sensors prove invaluable when detecting weak signals in a noisy environment and when a multipath propagation situation prevails, especially when space for deployment is restricted.

Besides aquatic environments, MMT ventures into precision positioning and motion control technology with its unique land-based displacement actuators. This segment features the single-crystal Hi-Fi multi-stake actuators (US Patent No. U.S. 9,673,374B2) for hysteresis-free displacement control of the light platform. The portfolio is further enhanced by the high-authority piezoelectric actuator (HAPA) (WIPO/PCT Patent No. WO/2017 17629 A1) and HAPA-driven flextensional actuators, distinguished by their piezoceramic stack drives. The latter actuators deliver a stroke or blocking force that is superior to traditional stacked or flex-tensional designs. MMT actuators are ideal for precision motion and displacement control tasks in laser-based technologies and systems.

Forging The Future

MMT is at the forefront of advancing PZN-PT crystals, focusing on growing larger sizes to reduce costs and exploring ternary and doped variations to enhance their properties. This initiative has led to the production of crystals with approximately double the power density of their binary counterparts, marking a significant advancement in device functionality. The company is actively working on scaling production and developing high Curie temperature crystals to meet the demands of more challenging applications.

Operating as an original design manufacturer (ODM) and original equipment manufacturer (OEM), MMT extends its expertise beyond the defense industry, most notably as the OEM for highly sought-after transducers used in down-hole exploration. The company is keen on fostering partnerships and inviting technology collaborators to venture into the uncharted territories of piezoelectric technology. MMT’s goal is not just to improve existing applications but also to forge new paths in areas that were previously considered unattainable.

This cooperative venture focuses on enhancing system performance and setting new technological benchmarks. As a company engaged in the research, development, manufacturing, and marketing of materials and devices, MMT significantly boosts the value of its partners’ systems, especially those that rely on high-performance transducers. MMT emphasizes a collective commitment to advancement and is open to non-exclusive technology transfers, promoting an unhindered flow of knowledge.

MMT stands as a pillar of innovation, transforming the landscape of piezoelectric technology. The firm, with its commitment to collaboration, excellence, and forward-thinking, plays a pivotal role as a contributor and pioneer in shaping the future of technology alongside its esteemed partners.