Resonant Acoustic Microsystems

Research

Our group develops microelectromechanical systems (MEMS) that use acoustics for signal processing, sensing, and computing, with emerging applications in quantum and optomechanical systems. Our long-term vision is to make acoustics a universal medium for energy- and size-efficient signal transduction, sensing, and processing across RF, photonic, and other domains. Current research in the lab is organized around three tightly connected thrusts: sub-THz piezoelectric acoustics and RF front ends, MEMS beyond RF, and heterogeneous integration with cross-domain interfaces.

These efforts combine thin-film piezoelectric materials, acoustic and electromagnetic co-design, microfabrication, precision microwave metrology, and heterogeneous integration to realize compact front-end components, sensors, transducers, and hybrid microsystems. Representative publications are listed below under each research area.

Thrust 1: Sub-THz Piezoelectric Acoustics & RF Front Ends

We develop thin-film piezoelectric resonators, filters, delay lines, couplers, and surface acoustic wave devices that push acoustic signal processing deep into the millimeter-wave and sub-terahertz regime. This thrust combines frequency scaling, loss engineering, multilayer and solidly mounted platforms, and electromagnetic–acoustic co-design to achieve compact low-loss front-end components for future wireless systems.

Selected projects include multilayer lithium niobate resonators beyond 100 GHz, compact 50 GHz acoustic filters, high-frequency surface acoustic wave devices on silicon carbide, and scalable low-loss piezoelectric platforms for millimeter-wave signal processing.

Representative publications

  1. O. Barrera, J. Kramer, L. Matto, V. Chulukhadze, S. Cho, M. Liao, M. S. Goorsky, and R. Lu, “50 GHz piezoelectric acoustic filter,” IEEE J. Microw., pp. 1–10, 2026, doi: 10.1109/JMW.2026.3661341.
  2. J. Kramer, B. T. Bosworth, L. Matto, N. R. Jungwirth, O. Barrera, F. Bergmann, S. Cho, V. Chulukhadze, M. Goorsky, N. D. Orloff, and R. Lu, “Acoustic resonators above 100 GHz,” Appl. Phys. Lett., vol. 127, no. 1, Art. no. 012204, 2025, doi: 10.1063/5.0275691.
  3. V. Chulukhadze, Y. Wang, L. Matto, M. E. Liao, I. Anderson, J. Kramer, S. Cho, M. S. Goorsky, and R. Lu, “Toward miniature high-coupling lithium niobate thin-film bulk acoustic wave resonators at millimeter wave,” IEEE Trans. Electron Devices, vol. 73, no. 2, pp. 988–994, Feb. 2026, doi: 10.1109/TED.2025.3644272.
  4. T.-H. Hsu, L. Matto, J. Campbell, J. Kramer, Z.-Q. Lee, I. Anderson, K. Chow, M. S. Goorsky, M.-H. Li, and R. Lu, “Toward mmWave surface acoustic wave resonators in lithium niobate on silicon carbide,” IEEE Trans. Ultrason., Ferroelectr., Freq. Control, vol. 72, no. 11, pp. 1522–1532, Nov. 2025, doi: 10.1109/TUFFC.2025.3611298.
  5. J. Campbell, T.-H. Hsu, L. Matto, N. Ahmed, M. Chaudhari, Z. Du, I. Anderson, J. Kramer, V. Chulukhadze, K. Chow, M.-H. Li, M. S. Goorsky, and R. Lu, “52 GHz surface acoustic wave resonators in thin-film lithium niobate on silicon carbide,” IEEE Trans. Ultrason., Ferroelectr., Freq. Control, vol. 72, no. 2, pp. 275–282, Feb. 2025, doi: 10.1109/TUFFC.2024.3522042.

Thrust 2: MEMS Beyond RF

We translate recent thin-film piezoelectric advances into ultrasound and sensing, power electronics, and engineered nonlinearity. Current directions include high-sensitivity ultrasonic transducers, high-temperature acoustic devices, compact resonators and transformers for power conversion, and nonlinear acoustic elements for phononic comb generation and frequency conversion.

Selected projects include lithium niobate bimorph PMUTs, harsh-environment transducers operating to elevated temperatures, nonlinear phononic devices, and spurious-free resonators and transformers for compact power conversion.

Representative publications

  1. I. Anderson, J. Kramer, T.-H. Hsu, Y. Wang, V. Chulukhadze, and R. Lu, “Phononic combs in lithium niobate acoustic resonators,” Appl. Phys. Lett., vol. 128, no. 5, Art. no. 052201, 2026, doi: 10.1063/5.0304587.
  2. M. Chaudhari, L. Matto, N. Ahmed, M. Liao, V. Tallavajhula, Y. Long, Z. Yao, J. Campbell, T.-H. Hsu, M. S. Goorsky, and R. Lu, “Thermal endurance of suspended thin-film lithium niobate up to 800 °C,” IEEE Trans. Ultrason., Ferroelectr., Freq. Control, 2025, doi: 10.1109/TUSON.2025.3650497.
  3. Z. Yao, V. Chulukhadze, Z. Liu, X. Niu, T.-H. Hsu, B. Kim, N. Hall, and R. Lu, “Bimorph lithium niobate piezoelectric micromachined ultrasonic transducer,” in Proc. IEEE Int. Ultrason. Symp. (IUS), Utrecht, Netherlands, Sept. 15–18, 2025.
  4. K. Nguyen, V. Chulukhadze, E. Stolt, W. Braun, J. Segovia-Fernandez, S. Chakraborty, J. Rivas-Davila, and R. Lu, “Near spurious-free thickness shear mode lithium niobate resonator for piezoelectric power conversion,” IEEE Trans. Ultrason., Ferroelectr., Freq. Control, 2023, doi: 10.1109/TUFFC.2023.3303123.
  5. Z. Yao, H. Chang, E. Stolt, C. Daniel, T.-H. Hsu, J. Rivas-Davila, and R. Lu, “Radial mode lithium niobate Rosen transformer,” in Proc. IEEE 39th Int. Conf. Micro Electro Mechanical Syst. (MEMS), Salzburg, Austria, Jan. 25–29, 2026.
  6. R. Lu, M. Breen, A. E. Hassanien, Y. Yang, and S. Gong, “A piezoelectric micromachined ultrasonic transducer using thin-film lithium niobate,” J. Microelectromech. Syst., vol. 29, no. 6, pp. 1412–1414, Dec. 2020, doi: 10.1109/JMEMS.2020.3026547.

Thrust 3: Heterogeneous Integration & Cross-Domain Interfaces

We use acoustics as an interface across electronics, photonics, thermal and infrared sensing, magnetics, and other domains. This thrust emphasizes transferred and bonded piezoelectric stacks, stress engineering, solidly mounted architectures, and co-design with optics, quantum systems, and heterogeneous materials to enable more integrated acoustic microsystems.

Selected projects include multilayer piezoelectric platforms, transferred thin-film lithium niobate stacks, scandium aluminum nitride solidly mounted devices, stress-managed piezoelectric films, and heterogeneous acoustic interfaces on diamond and other advanced substrates.

Representative publications

  1. J. Kramer and R. Lu, “A generalized acoustic framework for multilayer piezoelectric platforms,” IEEE Trans. Ultrason., Ferroelectr., Freq. Control, vol. 72, no. 9, pp. 1302–1311, Sept. 2025, doi: 10.1109/TUFFC.2025.3595433.
  2. T. Zhang, Y.-W. Chang, O. Barrera, N. Ahmed, J. Kramer, and R. Lu, “Acoustic and electromagnetic co-modeling of piezoelectric devices at millimeter wave,” IEEE J. Microelectromech. Syst., vol. 33, no. 5, pp. 640–645, Oct. 2024, doi: 10.1109/JMEMS.2024.3431576.
  3. Y. Wang, B. Kim, N. Ravi, K. Saha, S. Dasgupta, V. Chulukhadze, E. Kwon, L. Matto, P. Simeoni, O. Barrera, I. Anderson, T.-H. Hsu, J. Hou, M. Rinaldi, M. S. Goorsky, and R. Lu, “62.6 GHz ScAlN solidly mounted acoustic resonators,” Appl. Phys. Lett., vol. 128, no. 4, Art. no. 042201, 2026, doi: 10.1063/5.0306947.
  4. T.-H. Hsu, K. Saha, J. Kramer, O. Barrera, R. Zhang, P. Simeoni, M. Rinaldi, and R. Lu, “Ku-band AlScN-on-diamond SAW resonators with phase velocity above 8600 m/s,” in Proc. 23rd Int. Conf. Solid-State Sensors, Actuators and Microsystems (Transducers), Orlando, FL, USA, Jun. 29–Jul. 3, 2025, pp. 172–175, doi: 10.1109/Transducers61432.2025.11109438.
  5. B. Kim, I. Anderson, T.-H. Hsu, Z. Yao, M. Chaudhari, S. Cho, and R. Lu, “Residual stress anisotropy in thin-film lithium niobate for stress-managed MEMS,” in Proc. IEEE 39th Int. Conf. Micro Electro Mechanical Syst. (MEMS), Salzburg, Austria, Jan. 25–29, 2026.
  6. O. Barrera, S. Cho, K. Hyunh, J. Kramer, M. Liao, V. Chulukhadze, L. Matto, M. S. Goorsky, and R. Lu, “Transferred thin-film lithium niobate as millimeter-wave acoustic filter platforms,” in Proc. IEEE 37th Int. Conf. Micro Electro Mech. Syst. (MEMS), Austin, TX, USA, Jan. 21–25, 2024.