More Like this

1. HIGH-SPL PMUT ARRAY FOR MID-AIR HAPTIC INTERFACE

   Xia, F.; Peng, Y.; Yue, W.; Chen, C.-M.; Pala, S.; Arakawa, R. and (June 2023, 22th International Conference on Solid-State Sensors, Actuators and Microsystems-Transducers 2023)

   This paper presents a mid-air haptic interface device enabled by a piezoelectric micromachined ultrasonic transducer (pMUT) array achieving an unprecedentedly high transmission pressure of 2900 Pa at a 15 mm distance for the first time. The structure is based on sputtered potassium sodium niobate (K,Na)NbO3 (KNN) thin film with a high piezoelectric coefficient (𝑒𝑒31 ~ 8-10 C/m2). A prototype KNN pMUT array composed of 15×15 dual-electrode circular-shape diaphragms exhibits a resonant frequency around 92.4 kHz. Testing results show a transmitting sensitivity of 120.8 Pa/cm2 per volt under only 12 Vp-p excitation at the natural focal point of 15 mm away, which is at least 3 times that of previously reported AlN pMUTs at a similar frequency. Furthermore, an instant non-contact haptic stimulation of wind-like sensation on human palms has been realized. As such, this work sheds light on a new class of pMUT array with high acoustic output pressure for human-machine interface applications, such as consumer electronics and AR/VR systems. 

   more » « less
2. Mid-Air Particle Manipulations by a 2x2 PMUT Array

   Yue, W; Teng, M; Peng, Y; Xia, F; Tsao, P; Gao, Y; Ikeuch, S; Aida, Y; Umezawa, S; Lin, L (June 2024, Transducers Research Foundation)

   This work reports a platform based on ultrasound for mid-air particle manipulations using a 2×2 piezoelectric micromachined ultrasonic transducer (pMUT) array. Three achievements have been demonstrated as compared to the state-of-art: (1) high SPL (sound pressure level) of 120 dB at a distance 12 mm away by an individual lithium-niobate pMUT; (2) a numerically simulated and experimentally demonstrated 2D focal point control scheme by adjusting the phase-delay of individual pMUTs; and (3) the experimental demonstration of moving a 0.7 mg foam plastic particle of 12 mm away in the mid-air by ~1.8 mm. As such, this work shows the potential for practical applications in the broad fields of non-contact actuations, including particle manipulations in microfluidics, touchless haptic sensations, … etc. 

   more » « less
3. IMPROVED PERFORMANCE OF PASSIVE LAYER-FREE CURVED PMUT ARRAY

   Huang, Chichen; Khandare, Shubham; Kothapalli, Sri-Rajasekhar; Tadigadapa, Srinivas (June 2024, Proceeding of the Solid Sensors, Actuators and Microsystems Workshop 2024, Hilton Head)

   Chan, Jenna F; Rajaraman, Swaminathan (Ed.)

   We have successfully demonstrated a novel, passive layer-free, curved piezoelectric micromachined ultrasound transducer (PMUT) array, using a sacrificial curved glass template and 30% scandium-doped aluminum nitride (Sc-AlN) as the active layer. The PMUTs were fabricated using a curved, suspended borosilicate glass template created via a chip-scale glass-blowing technique, onto which electrodes and the piezoelectric layer were deposited. The glass layer was thereafter selectively removed. We characterized the performance of a 13 × 13 curved PMUT (cPMUT) array using an electrical impedance analyzer, a Laser Doppler Vibrometer (LDV), and hydrophone pressure measurements. Our results reveal a device resonance frequency of approximately 1.8 MHz in air, with LDV analysis indicating a significantly enhanced low-frequency response of 1.68 nm/V—a fivefold improvement over conventional curved PMUTs with a passive layer. Additionally, acoustic characterization in water showed that this array generates an acoustic pressure of approximately 80 kPa at a 4.4 mm focal distance, with a beam width of 5 mm, and achieves a spatial peak pulse average intensity (ISPPA) of 216 mW/cm2 when driven off-resonance. Furthermore, we demonstrate 20-degree steering capability using our data acquisition system. These advancements highlight significant potential for enhancing the precision and efficacy of medical imaging and therapeutic applications, particularly in ultrasonic diagnostics and treatments. 

   more » « less
4. AUTO-POSITIONING AND HAPTIC STIMULATIONS VIA A 35 MM SQUARE PMUT ARRAY

   https://doi.org/10.1109/MEMS49605.2023.10052452  

   Yue, W.; Peng, Y.; Liu, H.; Xia, F.; Sui, F.; Umezawa, S.; Ikeuchi, S.; Aida, Y.; and Lin, L. (January 2023, 2023 IEEE 36th International Conference on Micro Electro Mechanical Systems (MEMS))

   This work reports an engineered platform for the non-contact haptic stimulation on human skins by means of an array of piezoelectric micromachined ultrasonic transducer (pMUT) via the beamforming scheme. Compared to the state-of-art reports, three distinctive achievements have been demonstrated: (1) individual single pMUT unit based on lithium niobate (LN) with measured high SPL (sound pressure level) of 133 dB at 2 mm away; (2) a beamforming scheme simulated and experimentally proved to generate ~2.3x higher pressure near the focal point; and (3) the combination of auto-positioning and haptic stimulations on volunteers with the smallest reported physical device size to achieve haptic sensations. As such, this work could have practical applications in the broad areas to stimulate haptic sensations, such as AR (Augmented Reality), VR (Virtual Reality), and robotics. 

   more » « less
5. Design Approaches and Electromechanical Modeling of Conformable Piezoelectric‐Based Ultrasound Systems

   https://doi.org/10.1002/adsr.202300175  

   Amiri, Nikta; Shah, Aastha; Bhayadia, Amit_Kumar; Yu, Chia‐Chen; Karami, M_Amin; Dagdeviren, Canan (May 2024, Advanced Sensor Research)

   Abstract Painless, needleless delivery of drugs through the skin can be realized through aphenomenon called sonophoresis by applying an ultrasound field to the biological tissue. Development of wearable embodiments of such systems demands comprehensive characterization of both the physical mechanism of sonophoresisas well as wearability parameters. Here, we present a framework for analyzing disk‐type piezoelectric transducers in a polymeric substrate to create acoustic cavitation in a fluid coupling medium for sonophoresis applications. The device design and operating parameters such as the working frequency, applied voltage range, acoustic pressure distribution, and transducer spacing were determine dusing a finite element methods (FEM),and verified with experimental measurements. The influence of the surrounding water and tank reflections on the acoustic pressure field, and the interaction between the elements in the array structure were also studied.Finally, the impact of skin and the substrate geometry on the acoustic pressure fields was characterized to simulate the invivo use‐case of the system. These analytical models can be used to guide critical parameters for device design such as the separation distance of the piezoelectric transducer from the skin boundary. We envision that this tool boxwill support rapid design iteration for realization of wearable ultrasound systems. 

   more » « less