Optoelectronic tweezers: a versatile toolbox for nano-/micro-manipulation

Abstract

This review covers the fundamentals, recent progress and state-of-the-art applications of optoelectronic tweezers technology, and demonstrates that optoelectronic tweezers technology is a versatile and powerful toolbox for nano-/micro-manipulation.

Steering Micromotors via Reprogrammable Optoelectronic Paths

“…First, there is a large body of research that uses optoelectronic tweezers (OET) for manipulating micro-objects such as micro-/nanoparticles, microrobots, and cells . Both our work and other OET works rely on the same light-induced nonuniform electric fields and achieved seemingly similar trapping and controlled transport of micro-objects along predefined trajectories. − However, one of the main distinctions of the current work from other OET works is the target being manipulated.…”

“…First, ACEO reaches its maximum at a critical charging frequency f c , above which ions cannot follow the change in the electric field directions and cannot generate strong electroosmotic flows. f c is given by f c = σ normalm λ normalD 2 π ε L where σ m and ε are the conductivity and permittivity of the medium, λ D is the thickness of the electrical double layer (i.e., the Debye length), and L is the chamber height. In our experiment in 0.1 mM NaCl solution (see explanation of choosing this medium liquid in the SI file), f c = 280 Hz, orders of magnitude smaller than the typical driving frequency of 100 kHz.…”

“…The optoelectronic effect has been exploited extensively in optoelectronic tweezers (OET) to manipulate microparticles and cells. 42 The key device of this technology is a photoconductive substrate that switches from being an insulator to a conductor upon irradiation of light of proper wavelengths. When an electric field is applied vertical to the photoconductive substrate, the electric field's strength reaches its maximum at the edges of the light pattern.…”

A review on microrobots driven by optical and magnetic fields

“…75 Based on light-induced dielectrophoresis (DEP) force, OET combines the merits of optics and electronics and offers a user-friendly approach that enables programmable, touch-free and reliable manipulation of micro-/nano-sized objects. 76 Different from OT which require a coherent laser light source with high optical intensities, the optical source in an OET system can be a digital micromirror device (DMD) with a LED, 77,78 which is used to project animated light patterns onto a photoconductive substrate [in most cases, hydrogenated amorphous silicon (a-Si:H)]. OET relies on the unique features of the photoconductive substrate: in the dark, the impedance of the photoconductive substrate is high and it behaves like a resistor; when the photoconductive substrate is illuminated with light, its impedance is reduced significantly and the photoconductive substrate behaves like a conductor.…”

“…86 Ming Wu, the inventor of OET, founded Berkeley Lights Inc. together with Igor Khandros and William Davidow. 76 This California-based company has successfully commercialized fully automated OET instruments to enable the functional screening and selection of individual cells for antibody discovery, 87,88 cell line development, 89,90 cell therapy development 91 and synthetic biology. 92 Microrobots driven by heat-mediated optical manipulation techniques.…”