# Light Programmable Micro/Nanomotors with Optically Tunable In-Phase Electric Polarization

## TL;DR

This paper introduces a light-controlled mechanism for reorienting semiconductor nanowires in electric fields, enabling programmable nanomotors with rapid, reversible alignment changes driven by optically tuned electrical polarization.

## Contribution

It demonstrates a novel optically tunable polarization mechanism that allows instant, reversible control of nanowire alignment and motion, leading to reconfigurable nanomotors.

## Key findings

- Nanowire alignment can be switched hundreds of times with visible light.
- The mechanism is based on optically tuned in-phase electrical polarization.
- A new microscale stepper motor concept is demonstrated.

## Abstract

To develop active nanomaterials that can instantly respond to external stimuli with designed mechanical motions is an important step towards the realization of nanomachines and nanorobots. Herein, we present our finding of a versatile working mechanism that allows instantaneous change of alignment direction and speed of semiconductor nanowires in an external electric field with simple visible-light exposure. The light induced alignment switch can be cycled over hundreds of times and programmed to express words in Morse code. With theoretical analysis and numerical simulation, the working principle can be attributed to the optically tuned real-part (in-phase) electrical polarization of a semiconductor nanowire in an aqueous suspension. The manipulation principle is exploited to create a new type of microscale stepper motor that can readily switch between in-phase and out-phase modes, and agilely operate independent of neighboring motors with patterned light. This work could inspire the development of a new type of micro/nanomachines with individual and reconfigurable maneuverability for many applications.

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Source: https://tomesphere.com/paper/1905.02140