Recently, a research team led by Dr. DU Xuemin from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences, has reported a novelphotopyroelectric tweezer (PPT) that combine the advantages of light and electric fields. Using a rationally designed photopyroelectric substrate with efficient and durable photo-induced surface charge-generation, it enables versatile manipulation in various working scenarios.

This work was published in The Innovation on Dec. 12.

Optical tweezers and related techniques provide extraordinary opportunities for research and applications in physical, biological, and medical. However, requirements such as high-intensity laser beams, complex electrode designs, additional electric sources, or low-conductive media, significantly limit their flexibility and adaptability, hindering practical applications.

In this study, researchers propose a PPT consisting of two key components: a a near infrared spectrum (NIR) laser light source and a PPT device that includes a liquid medium and a photopyroelectric substrate.

The photopyroelectric substrate comprises a superhydrophobic ferroelectric polymer layer made of Ga-In liquid metal microparticle-embedded poly (vinylidene fluoride-co-trifluoroethylene) (LMPs/P(VDF-TrFE)) composites, and a lubricant-infused slippery layer. The polymer layer generates real-time surface charges via the photopyroelectric effect, while the lubricant layer reduces motion resistance, suppresses contamination, and prevents charge screening by conductive media.

Owing to its rationally designed structure, the PPT efficiently and durably generates surface charges when exposed to low-intensity near-infrared (NIR, as low as ~ 8.3 mW mm^-2) irradiation. This induces a strong driving force (up to ~ 4.6×10^-5 N) without requiring high-intensity laser beam, complex electrode designs, or additional electric sources.

"The innovation of the PPT lies in the rational design of the photopyroelectric substrate, which efficiently generation charges, and the lubricant layer that prevents charge screening by conductive media. This design imparts unparalleled flexibility and adaptability for diverse object manipulation," said Dr. DU.

The PPT can remotely and programmably manipulate objects of diverse materials (polymer, inorganic, and metal), phases (bubble, liquid, and solid), and geometries (sphere, cuboid, and wire).

Moreover, the PPT is adaptable to various media with wide-range conductivities (0.001 mS cm^-1 ~ 91.0 mS cm^-1) and is versatile for both portable macroscopic manipulation platform and microscopic manipulation system. It supports on-demand manipulating area (12.5 ~ 96.0 cm²), enabling cross-scale manipulations for solid objects ranging from 5 μm to 2.5 mm, liquid droplets (1 pL to 10 mL), and biological samples from single cell to cell assemblies.

The proposed PPT overcomes limitations of conventional tweezers, bridging macroscopic and microscopic manipulations, and offers an innovative tool for robotics, colloidal science, organoids, tissue engineering, and neuromodulation.

PPT-photopyroelectric tweezer for versatile manipulation. (Image by SIAT)

Media Contact: LU Qun

Email: qun.lu@siat.ac.cn

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Photopyroelectric tweezers for versatile manipulation