The Future of Contactless Manipulation: Acoustic Waves vs. Lasers and EM Fields

Acoustically gathered microparticles

How do you move something without touching it? It may sound like the stuff of science fiction but new contactless manipulation technologies are revolutionising how we interact with the physical world allowing objects to be moved, shaped, or controlled without direct touch.

At Impulsonics, we’re leading the charge on acoustic manipulation in our mission to make biotech automation simpler but there are other emerging technologies.

Unlike traditional contactless systems focused on communication or sensing, these technologies enable physical interaction at a distance, opening new possibilities in medicine, manufacturing, robotics, and consumer electronics. The most promising approaches alongside acoustic waves are lasers, and electromagnetic (EM) fields, each offering unique capabilities and challenges.

Acoustic Waves

Use case: moving millions of cells at once

Acoustic levitation

Acoustic manipulation uses sound waves - typically in the ultrasonic range - to exert force on particles or objects. This is achieved through pressure nodes created by standing waves, which can trap and move small items like droplets, cells, or even tiny tools. Though acoustics tweezers already exist in biomedical research to sort cells, our innovative use of this technology allows for a much wider functionality including full cell passaging.

A key strength of acoustic waves in biotechnology is their ability to interact with cells totally label-free.

The key advantage of acoustic manipulation is its safety and compatibility with soft matter. It’s non-invasive, gentle, and energy-efficient, making it ideal for applications in tissue engineering in drug discovery.

Lasers

Use case: precise movement of one cell at a time

A nanoparticle (diameter 103 nm) trapped by an optical tweezer. Credit - Steven Hoekstra

Laser-based manipulation, particularly through optical tweezers, uses highly focused light beams to trap and move microscopic particles. This technique has been instrumental in biological research – winning the Nobel Prize in Physics in 2018 -  and allowing scientists to manipulate DNA strands, proteins, and cells with nanometre precision.

Lasers offer exceptional accuracy and control, especially at micro and nano scales. However, their narrow focus means that to move something you need to know exactly where it is in space. This can be helpful for precision but makes them less robust. They can operate in sterile environments and are compatible with transparent materials, making them ideal for medical and semiconductor applications. However, they require line-of-sight and can be hazardous if not properly managed.

High energy consumption and the need for precise calibration also limit their scalability for larger or more dynamic systems. Given the sensitivity of optical tweezers they are also not typically compatible with off the shelf plastic labware, meaning that they are harder to integrate into high throughput systems.

Electromagnetic Fields

Use case: Aerosols…and trains!

Shanghai Maglev Train. Credit - Max Talbot-MInkin

EM field manipulation involves using electric or magnetic fields to move or control objects, often through induced currents or magnetic forces. This includes technologies like magnetic levitation, capacitive control, and dielectrophoresis (utlising the force created in non-uniform electric fields). In robotics, EM fields are used to guide magnetic microrobots through the human body for targeted therapy. In consumer electronics, capacitive fields enable touchless gesture control on smartphones and smart appliances.

In biotechnology, magnetic beads are often used in DNA extraction. This is a simple but effective technique for cleaning crude samples. A key weakness, however, is that for effective use they normally only interact with existing magnetic materials. This means they can’t be used label-free.

While technically facets of the same technology, electrostatic levitation can also be used to levitate small droplets by applying a static electrical field. We didn’t have to go far to find a real-world example as Microsol, who share a building with us, use this technique to help understand aerosol behaviour and support drug formulation with great success.

EM fields are versatile and can penetrate materials, allowing for hidden or embedded control systems. They support remote actuation and can manipulate a wide range of materials, including metals and biological tissues. However, they are sensitive to interference and may pose risks to nearby electronics. Security and stability in dynamic environments remain ongoing challenges.

Future Trends

Given the critical importance of sterility in biotechnology, contactless manipulation only looks to become more important in the future. As the oldest technology it is not surprising that magnetic blocks are ubiquitous. Meanwhile, the Echo Liquid Handler has become an essential part of many labs.

Finding the right tool for the job will be critical to enable these technologies to thrive inside and outside of the lab. While motion stages and pumps will surely remain workhorses of any lab instrument, remote fields will offer a step change in capabilities delivering transformational advances forward that will unlock the next biotechnology revolution.

As we reach the quarter mark of the biotech century, we must surely stop relying on the tools of 20th to make it happen.