A surprising experiment opens the path to new particle manipulation methods

Unexpected result from acoustics experiment could have applications in biomedical and microsystems research
A surprising experiment opens the path to new particle manipulation methods
(a-b) Heavy particles move towards antinodes of a submerged vibrating plate. (c-d) Single particles and (e-f) a swarm of particles move on pre-defined trajectories on the plate by playing carefully-chosen musical notes. Image: Kourosh Latifi

Researchers at Aalto University have discovered a surprising phenomenon that changes how we think about how sound can move particles. Their experiment is based on a famous experiment recognisable from high school science classrooms worldwide – the Chlandni Plate experiment, where particles move on a vibrating surface. The experiment was first performed in from 1787 by Ernst Chladni, who is now known as the father of acoustics. Chladni’s experiment showed that when a plate is vibrating at a frequency, heavy particles move towards the regions with less vibration, called nodal lines. This experiment has been extensively repeated during the centuries since, and shaped the common understanding of how heavy particles move on a vibrating plate. But researchers at Aalto University have now shown a case where heavy particles move towards the regions with more vibrations, or antinodes. “This is a surprising result, almost a contradiction to common beliefs,” says Professor Quan Zhou.

The researchers installed a silicon plate on a piezoelectric transducer and submerged it into water. They spread sub-mm glass spheres on the plate, and vibrated the plate with signals of different frequencies, creating waves on the plate. The researchers were then surprised to observe that the particles move towards the antinodes, forming what they have dubbed “inverse Chladni patterns”.

An interesting aspect is that the system can create predictable motion at a wide range of frequencies. “We can move particles at almost any frequency, and we do not rely on the resonance of the plate”, says Zhou. “This gives us a lot of freedom in motion control”. 

Using the newly discovered phenomenon, the researchers were able to precisely control the motion of single particles and a swarm of particles on the submerged plate. In one example, they moved a particle in a maze on the plate, wrote words consisting of separate letters, and merged, transported and separated a swarm of particles by playing different musical notes.

“Many procedures in pharmaceutical research and microsystem assembly require the ability to move and manipulate small particles easily. Using just a single actuator to do all these different things, we are opening a path to new particle handling techniques”, says Zhou. “Additionally, the method can inspire the future factory-on-a-chip systems.”

Link to the article

Contact:

Professor Quan Zhou

[email protected]

  • Published:
  • Updated:
Share
URL copied!

Related news

Head of Post-Award Services Jukka Hyvönen and Head of Pre-Award Services Sanna-Maija Kiviranta
Appointments, Research & Art Published:

New Service Heads at Research Services

Sanna-Maija Kiviranta has been appointed as Head of Pre-Award Services and Jukka Hyvönen has been appointed as Head of Post-Award Services. Both teams support Aalto University's researchers in research funding.
A false colour electron microscope image of the bolometer, the scale bar shows a single bacteria, indicating how small the device is
Research & Art Published:

Radiation detector with the lowest noise in the world boosts quantum work

The nanoscale radiation detector is a hundred times faster than its predecessors, and can function without interruption
The details avaiable on the page in a picture with a colourful cartoon of an antropomorphic qubit
Campus, Research & Art Published:

From quantum gateways to super-refrigerators – the quantum technology revolution arrives in Otaniemi

An exhibition uncovering the secrets of quantum technology is opening on 17 October as part of the quantum technology summit
Kuva: Mostphotos
Cooperation, Research & Art Published:

Helsinki Brain & Mind, a new neuroscience hub, awar­ded ERDF fund­ing

The European Regional Development Fund has awarded €500,000 to the University of Helsinki, Aalto University and the Helsinki University Hospital for the development of a research, competence and innovation hub in neuroscience.