Scientists at the Australian Research Council's Centre of Excellence for Transformative Meta-Optical Systems (TMOS) have developed a novel way to generate a tractor beam, potentially leading to less invasive medical procedures. This miniature version of the fictional device, capable of pulling objects toward it, uses a 2-micrometer-thick silicon metasurface to transform a standard light beam into a triple spiral "solenoid" beam.
The technology promises to revolutionize medical practices like biopsies. Currently, these procedures often involve needles or forceps, causing cell trauma. The tractor beam, on the other hand, could potentially draw out cells with minimal damage. This would lead to safer and less painful medical treatments.
This new approach utilizes a metasurface, a micro-etched surface designed to modify electromagnetic waves. In this case, the metasurface acts like a light stencil, converting a conventional light beam into a three-stranded spiral beam resembling a tunnel. This triple helix solenoid beam exhibits a unique property: it attracts particles instead of pushing them away.
The mechanism resembles how a drill bit pulls sawdust. The three strands of the beam cradle the target particle, providing a traction effect. This "tractor-ing" motion, unlike the simple holding capabilities of standard optical tweezers, is crucial for the beam's ability to pull objects.
While the concept of a solenoid beam is not entirely new, this research focuses on optimizing its production. Previous attempts relied on bulky spatial light modulators (SLMs), making the technology impractical for handheld applications. The TMOS team's breakthrough lies in using a significantly smaller metasurface made of silicon. This not only reduces the size and weight but also improves efficiency and cost-effectiveness.
This research, published in the journal *ACS Photonics*, focuses on the metasurface's effectiveness in transforming light into a coherent, high-quality solenoid beam. The researchers acknowledge that while the ability of the beam to attract particles has been established in previous research, their contribution lies in creating a more efficient and compact system for generating the beam itself.
The TMOS team believes this new metasurface could be a significant step towards making tractor beams a practical reality, opening up new possibilities for minimally invasive medical procedures and other applications.