Like teleportation, cloning, and invisibility, tractor beams are one of those old sci-fi movie clichés that many of us wish were real. But some researchers at MIT have just invented a miniaturized tractor beam that's small enough to fit on a chip. While it can't yet pull an entire battleship like in Star Wars, it can still manipulate biological particles like cells and DNA.
MIT has created a chip-based optical tractor beam that focuses a penetrating beam more than 5 millimeters from the chip surface. This may not sound like much, but it's a game-changer compared to previous integrated "optical tweezers" that could only work within a few microns of the chip. These old methods essentially removed cells from sterile glass containers (commonly used in biological experiments) and placed them directly on the surface of the chip, thereby increasing the risk of contamination.
This breakthrough changes these limitations. MIT's broader device can precisely capture biological samples and move them around them through glass while sealing them in a standard coverslip container. The entire process is kept clean and sterile.
As for how the microtractor beam works, it relies on a silicon photonic component called an integrated optical phased array. It uses semiconductor manufacturing processes to create arrays of tiny antennas on chips. Together, these antennas can shape and direct a focused beam simply by adjusting the timing of the light signal driving each antenna element.
According to the team, the system is "orders of magnitude better than previous demonstrations," as an MIT press release notes.
Another major improvement is that this new system reduces tractor beam functionality to chip size for the first time. Typical designs for the same purpose are not only limited in scope, but also quite bulky, requiring a large microscope to be installed in the laboratory, and multiple devices to shape and control the light.
To test their invention, the MIT engineers first used the chip to capture and manipulate tiny polystyrene spheres (the reference particles used in the experiments). Once that worked, they advanced to capturing and moving living cancer cells.
Although still in its early stages, its potential impact on biological research and even clinical applications is huge. This beam can be used to analyze DNA, classify cells, study the mechanisms of disease, and be used in a variety of new experimental and diagnostic tools.
The researchers also hope to continue improving the system, with goals including adding an adjustable beam focus, using multiple capture points simultaneously, and applying it to different biological systems.