The chip-based “tractor beam,” inspired by “Star Wars,” uses a tightly focused beam of light to capture and manipulate cells.
Credits:Credit: Sampson Wilcox, RLE
MIT researchers have created a compact, chip-based “tractor beam” device inspired by “Star Wars” for manipulating DNA and studying cells in biological research. This palm-sized device uses light from a silicon-photonics chip to handle particles millimetres from the surface, allowing for sterile conditions by penetrating glass covers. Unlike traditional bulky optical tweezers, this new technology is smaller, easier to manufacture, and suitable for high-throughput experiments. It employs an integrated optical phased array to trap and manipulate cells much further from the chip surface than previous devices, improving compatibility with standard biological experiments and reducing cell stress.
A new trapping modality
The researchers have innovated a silicon photonics chip that emits a beam of light capable of focusing about 5 millimetres above its surface. This advancement allows for capturing and manipulating biological particles within their sterile glass covers, preventing contamination and negating the need to replace the chip frequently. This new method enhances the practical application of optical tweezers in biological research.
Manipulating light
Using an integrated optical phased array consisting of microscale antennas fabricated on a chip through semiconductor processes, the researchers controlled the optical signals from each antenna to shape and steer a beam of light. Unlike earlier ones designed for long-range applications like lidar, this system enables the formation of tightly focused beams essential for optical tweezing. By adjusting the wavelength of the optical signals, they steered the focused beam with microscale accuracy over a range larger than a millimetre, suitable for optical trapping and tweezing a few millimetres away from the chip’s surface.
The team conducted initial tests with tiny polystyrene spheres and then advanced to manipulating cancer cells provided by the Voldman group. They developed techniques to semi-automatically track the motion of sample particles, determine the right trap strength to maintain particle position, and efficiently process data. These developments allowed them to showcase the first successful cell experiments using single-beam optical tweezers. Looking ahead, they plan to refine the system to allow adjustable focal heights and apply it to more complex biological manipulations involving multiple trap sites simultaneously.
