Science

Acoustic Holography: Using Sound Waves to Levitate Matter | with Sriram Subramanian

The Royal Institution
The Royal Institution•May 5, 2026

Why It Matters

Acoustic holography enables fast, contactless manipulation and tactile feedback, opening new possibilities for manufacturing, medical handling, and immersive consumer experiences.

Key Takeaways

  • •Acoustic levitation uses phased ultrasound arrays to trap particles
  • •Simple two‑speaker standing waves can levitate lightweight objects easily
  • •Real‑time phase control enables dynamic interactive shapes and haptic feedback
  • •Optimization reduces to focal‑point calculation, speeding computation dramatically for real‑time
  • •Iterative Gerchberg‑Saxton algorithm reconstructs arbitrary acoustic holograms in seconds

Summary

The video showcases acoustic holography, where precisely phased ultrasound arrays create standing‑wave patterns that can levitate and manipulate matter without physical contact. By adjusting the phase of each transducer, researchers generate stable acoustic traps that hold objects ranging from coffee beans to a mock burger, demonstrating both simple two‑speaker levitation and complex multi‑speaker configurations. Key technical insights include the use of 40 kHz ultrasound, the importance of phase delays to shape force fields, and a shift from computationally heavy nonlinear optimization to a fast focal‑point calculation. This two‑step method—identifying a focal point and adding a trap signature—delivers real‑time control at tens of thousands of frames per second. Live demos illustrate particles moving in sync with a presenter’s finger, providing tactile sensations that feel like wind, and even embedding audio into the levitated object. The team also solves the inverse problem of generating arbitrary acoustic holograms using an iterative Gerchberg‑Saxton algorithm, leveraging full amplitude and phase control unavailable in optics. These advances suggest a future where contactless manipulation, 3‑D haptic displays, and acoustic imaging become practical for manufacturing, medical handling, and immersive user interfaces, expanding the utility of sound beyond traditional communication.

Original Description

What if sound could do more than travel through space — what if it could reshape it?
This is a Friday Evening Discourse exploring one of the most extraordinary frontiers in modern engineering: using precisely computed sound fields to levitate objects, create three-dimensional shapes in mid-air, and generate physical sensations without any contact at all. Become a ScienceSupporter and watch the Q&A here: https://youtu.be/5NlTpe8d_7c
This Discourse was filmed on Friday 27 March 2026 at the Royal Institution.
Sriram Subramanian introduces the science of acoustic holography and levitation — explaining how ultrasound waves can be controlled to lift and guide tiny objects across a remarkable range of materials, from solids and liquids to powders and gases. He sets out the core principles behind shaping sound fields and the computational challenges of making them work in real environments. Sriram turns to the real-world applications of acoustic holography — demonstrating how these sound-based systems are opening up new possibilities in multi-sensory human-computer interaction, contact-free material handling, and life-science and biopharmaceutical research. He explores how dynamic three-dimensional shapes formed from sound can be both seen and physically felt, and what this means for the future of how we interact with digital and physical systems alike.
Continue watching in the Members Exclusive Q&A, where Sriram takes questions from the audience and Ri Director Katherine Mathieson.
Sriram Subramanian FREng is the Royal Academy of Engineering Chair in Emerging Technologies at University College London, where he leads research spanning acoustics, computation and human–computer interaction. Trained as an electrical communication engineer at the Indian Institute of Science, he took an unconventional path to a PhD in industrial design in the Netherlands — a background that continues to shape his distinctly cross-disciplinary approach to engineering.
His work has fundamentally advanced the field of acoustic manipulation, introducing ultrasound-based technologies capable of creating mid-air touch sensations, levitation and contactless control of physical matter. He co-founded Ultraleap (originally Ultrahaptics) to commercialise mid-air haptics technology, and more recently co-founded AcoustoFab, which develops contact-free acoustic robotic systems for laboratory automation and biopharmaceutical manufacturing. He has also established Metasonixx, working on reconfigurable acoustic metamaterials for adaptive sound control.
Sriram is a Fellow of the Royal Academy of Engineering, an IEEE Fellow, an ACM Distinguished Member, and a Fellow of the Optica Society. His work has been recognised with the Colin-Campbell Mitchell Award and has been covered by The Guardian, The Times and CNN. He is a committed advocate for science communication, using live demonstrations of levitation and holography to bring cutting-edge research to public audiences.
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#acousticholography #soundlevitation #SriramSubramanian #RoyalInstitution #multisensorysound #acousticlevitationscience #mid-airhaptics #ultrasound manipulation
#contact-free #robotics #3Dsoundfields #physicslecture #UCLresearch #humancomputerinteraction #biopharmatechnology #RiDiscourse

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