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1. Conformable surface acoustic wave biosensor for E-coli fabricated on PEN plastic film

   https://doi.org/10.1016/j.bios.2020.112164  

   Lamanna, Leonardo; Rizzi, Francesco; Bhethanabotla, Venkat R.; De Vittorio, Massimo (September 2020, Biosensors and Bioelectronics)

   null (Ed.)
2. Writable spin wave nanochannels in an artificial-spin-ice-mediated ferromagnetic thin film

   https://doi.org/10.1063/5.0085455  

   Li, Jianhua; Xu, Wen-Bing; Yue, Wen-Cheng; Yuan, Zixiong; Gao, Tan; Wang, Ting-Ting; Xiao, Zhi-Li; Lyu, Yang-Yang; Li, Chong; Wang, Chenguang; et al (March 2022, Applied Physics Letters)

   Magnonics, which employs spin-waves to transmit and process information, is a promising venue for low-power data processing. One of the major challenges is the local control of the spin-wave propagation path. Here, we introduce the concept of writable magnonics by taking advantage of the highly flexible reconfigurability and rewritability of artificial spin ice systems. Using micromagnetic simulations, we show that globally switchable spin-wave propagation and locally writable spin-wave nanochannels can be realized in a ferromagnetic thin film underlying an artificial pinwheel spin ice. The rewritable magnonics enabled by reconfigurable spin wave nanochannels provides a unique setting to design programmable magnonic circuits and logic devices for ultra-low power applications. 

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3. Frequency and Bandwidth Design Toward Millimeter-Wave Thin-Film Lithium Niobate Acoustic Filters

   https://doi.org/10.1109/LMWT.2025.3559400  

   Barrera, Omar; Anusorn, Taran; Cho, Sinwoo; Kramer, Jack; Chulukhadze, Vakhtang; Hsu, Tzu-Hsuan; Campbell, Joshua; Anderson, Ian; Lu, Ruochen (June 2025, IEEE Microwave and Wireless Technology Letters)

   This letter presents a versatile design method for achieving precise frequency and bandwidth control of compact acoustic filters monolithically at millimeter wave (mmWave) in transferred thin-film lithium niobate (LiNbO3). Prototypes are implemented with lateral field excited first-order antisymmetric (A1) mode bulk acoustic resonators (XBARs). The design leverages the in-plane anisotropy of the e15 piezoelectric coefficient in 128° Y-cut LiNbO3, enabling monolithic control of electromechanical coupling ( k2 ) by simply rotating the resonator layout. This allows for filters with customizable fractional bandwidths (FBWs). Additionally, fine-tuning of the center frequency ( fc ) is achieved through selective trimming of the film for series and shunt resonators, enabling a single design to be scaled across frequencies with enhanced fabrication tolerance. To validate the approach, we designed and fabricated a filter centered at 18.6GHz, achieving a low insertion loss (IL) of 1.84 dB, and a precise designed FBW of 9.5%. This platform shows a significant promise for enabling a monolithic filter bank with precise band selection, paving the way for the next generation of mmWave acoustic filters. 

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4. Miniature High-Coupling Lithium Niobate Thin Film Bulk Acoustic Wave Resonators at 10-30 GHz

   https://doi.org/10.1109/IMS40360.2025.11103794  

   Chulukhadze, Vakhtang; Wang, Yinan; Anderson, Ian; Kramer, Jack; Cho, Sinwoo; Lu, Ruochen (June 2025, IEEE)

   Thin film bulk acoustic wave resonators (FBARs) leveraging sputtered aluminum nitride (AlN) and scandium aluminum nitride (ScAlN) films, are a leading commercial solution for compact radio frequency (RF) filters in mobile devices. However, as 5G/6G bands extend beyond 6 GHz, achieving the required thinner piezoelectric film thicknesses below 500 nm presents a significant challenge to high-quality sputtering, resulting in a moderate quality factor (Q). Additionally, AlN/ScAlN platforms are limited by moderate electromechanical coupling (k2), restricting bandwidth. More recently, ultra-thin transferred single-crystal piezoelectric lithium niobate (LN) has enabled lateral field excited resonators (XBAR) at 10-30 GHz. While these devices boast a high Q and k2, they face challenges with low capacitance density, large footprint, and significant electromagnetic (EM) effects. On the other hand, thickness-field excited LN FBARs face challenges with bottom electrode integration. In this work, we implement a transferred LN on aluminum FBAR platform on sapphire wafers with an intermediate amorphous silicon layer without the need for a patterned bottom electrode. The resonators show first order symmetric mode (S1) at 10.5 GHz with a 3-dB series resonance Q of 38 and k2 of 14.1%, alongside third order symmetric mode (S3) at 27 GHz with a 3-dB series resonance Q of 22 and a high k2 of 11.3%. Further analysis shows that higher Q could be achieved by adjusting the low-loss piezoelectric to lossy metal volume ratio. 

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5. Electrically Tunable Surface Acoustic Wave Propagation at MHz Frequencies Based on Carbon Nanotube Thin‐Film Transistors

   https://doi.org/10.1002/adfm.202010744  

   Shen, Chen; Lu, Shiheng; Tian, Zhenhua; Yang, Shujie; Cardenas, Jorge_A; Li, Junfei; Peng, Xiuyuan; Huang, Tony_Jun; Franklin, Aaron_D; Cummer, Steven_A (February 2021, Advanced Functional Materials)

   Abstract Surface acoustic waves (SAWs) that propagate on the surface of a solid at MHz frequencies are widely used in sensing, communication, and acoustic tweezers. However, their properties are difficult to be tuned electrically, and current devices suffer from complicated configurations, complicated tuning mechanisms, or small ranges of tunability. Here a structure featuring a thin‐film transistor configuration is proposed to achieve electrically tunable SAW propagation based on conductivity tuning. When a DC gate voltage is applied, the on‐site conductivity of the piezoelectric substrate is modulated, which leads to velocity and amplitude tuning of SAWs. The use of carbon nanotubes and crystalline nanocellulose as the channel and gate materials results in high tuning capacity and low gate voltage requirement. The tunability is manifested by a 2.5% phase velocity tuning and near 10 dB on/off switching of the signals. The proposed device holds the potential for the next generation SAW‐based devices. 

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