Liwei Lin (Advisor)

Research Advised by Professor Liwei Lin

Lin Group:  List of Projects | List of Researchers

Ultrasound-Induced Haptic Sensations via PMUTs

Sedat Pala
Zhichun Shao
Yande Peng
Liwei Lin
2021

This work presents the sense of touch via non-contact ultrasonic waves by a dual-electrode bimorph piezoelectric micromachined transducer (pMUT) array. The prototype device has 12×12 elements with circular diaphragms of 415μm in radius made of 2μm-thick AlN. They are fabricated by a CMOS compatible micromachining process resulting a resonant frequency at 109.4kHz. Experimentally, a best haptic sensation on human fingers is found when emitting high frequency ultrasonic waves to emulate 100Hz signals by means of pulse width modulation with a 50% duty cycle. Strong haptic sensations are...

Ultrasound Induced Haptic Sensation by pMUTs

Sedat Pala
2021
Spring 2021 BSAC Research Review Presentation View Slides View Presentation

Piezoelectric Micromachined Ultrasonic Transducers With Pinned Boundary Structure

Yue Liang
Benjamin Eovino
Liwei Lin
2020

This paper reports the approach to boost the acoustic performances of PMUTs (Piezoelectric Micromachined Ultrasonic Transducers) including vibrational amplitude, acoustic pressure and electromechanical coupling by using the pinning boundary structure. An analytical model is developed based on an assumed mode shape and is validated with matching results from numerical simulations. Prototyped devices are fabricated and tested with a measured 2.5X improvement in displacement and 3.5X higher pressure output per volt at resonance as compared to those of PMUTs with clamped boundary. As a...

BPN934: Display Compatible pMUTs

Sedat Pala
2020

Ultrasonic transducers have been used in many applications from medical imaging to range finding. In recent years, applications have been further expanded to hand-held devices such as fingerprint sensors, and gesture recognitions thanks to advancements in micromachined ultrasonic transducers (MUTs). Compared to conventional ultrasound devices, MEMS ultrasonic transducers have advantages of higher resolution, higher bandwidth, and lower power consumption. More recently, products to interact electronic devices from a distance have been introduced. These products either require an allocated...

BPN917: Low-Cost, Efficient, Photolithography-Free Fabrication of Stretchable Electronics Systems on a Vinyl Cutter

Renxiao Xu
Peisheng He
2020

We present a new way for the fabrication of stretchable electronics systems without photolithography procedures by exploiting the through-cut, tunnel-cut, and blind-cut modes of a commercial desktop-size vinyl cutter. Compared to previous studies involving photolithography, our method produces a batch of representative devices in significantly reduced time (by ~69%) and cost (by ~73%) with similar feature sizes (100-1000um). Our inclusion of blind-cut and tunnel- cut modes facilitates the fabrication of complex stretchable electronics systems, rather than only electrodes and...

Renxiao Xu

Graduate Student Researcher
Mechanical Engineering
Professor Liwei Lin (Advisor)
Ph.D. 2020

Renxiao Xu received his B.E. (2013) from Huazhong University of Science and Technology, M.S. (2015) from Northwestern University, both in Mechanical Engineering. He is pursuing Ph.D. in Mechanical Engineering at UC Berkeley.

BPN918: Magnetically Powered, Untethered Soft Robots with Bioinspired Bone-and-Flesh Constructs

Renxiao Xu
Fanping Sui
2020

We present a new class of soft robots inspired by the bone-and-flesh construct in human body for fast, deterministic actuation. Two distinctive advancements have been achieved: (1) untethered robots with external magnetic power, boasting high normalized power density of ~2*10-2/s (40-6,000,000x higher than most reports); (2) ultrafast and deterministic-shape actuation in ~0.1 seconds (100x faster than the state-of-the-art). Inspired by the natural human architecture, our soft robots with different elastomer (flesh) structures and magnet (bone) placements can complete various tasks...

Pinned Boundary Piezoelectric Micromachined Ultrasonic Transducers (PMUT)

Yue Liang
2020

Ultrasound technologies can be applied to a variety of applications, such as medical imaging/therapeutics, materials assessment, flow rate measurement and others. Piezoelectric micromachined ultrasonic transducers (PMUTs) have advantages over the traditional bulk transducers in wide bandwidth, small size, and low cost. This work proposes to boost PMUT’s acoustic performance further including vibrational amplitude, acoustic pressure and electromechanical coupling by using the pinning boundary structure and to explore various new applications. The equivalent circuit model for pinned boundary...