Fabrication of quartz microcylinders by laser interference lithography for angular optical tweezers

Zhanna Santybayeva,Afaf Meghit,Benoit Charlot,Roland Teissier,Frederic Pichot,Francesco Pedaci,Rudy Desgarceaux,Charles De Marin

doi:10.1117/1.jmm.15.3.034507

Abstract

The use of optical tweezers (OTs) and spin angular momentum transfer to birefringent particles allows new mechanical measurements in systems where torque and rotation are relevant parameters at the single-molecule level. There is a growing interest in developing simple, fast, and inexpensive protocols to produce a large number of submicron scale cylinders of quartz, a positive uniaxial birefringent crystal, to be employed for such angular measurements in OTs. Here, we show that laser interference lithography, a method well known for its simplicity, fulfills these requirements and produces quartz cylindrical particles that we successfully use to apply and measure optical torque in the piconewton nm range in an optical torque wrench.

Highlights

In the last few decades, several technical breakthroughs have provided researchers with the ability to apply an external “force” to a microscopic particle in the piconewton range while measuring its position with subnanometer resolution
We spin-coat a thin layer of AZ 701 MIR photoresist (Merck Performance Materials GmbH) at 4000 rpm for 30 s, followed by soft baking at 95°C for 1 min
The quartz sample is exposed on the laser interference lithography (LIL) setup, prepared for a fixed interference period

Summary

Introduction

In the last few decades, several technical breakthroughs have provided researchers with the ability to apply an external “force” to a microscopic particle in the piconewton range while measuring its position with subnanometer resolution Since their development,[1] optical tweezers (OTs) have been of great interest for their all-optical manipulation capabilities and have proven their potential in several different applications in physics as well as in biology.[2] In particular, together with atomic force microscopes and magnetic tweezers,[3] OTs are routinely used to study biological systems at the singlemolecule level. The mechanical behavior of single biopolymers, such as DNA and the mechanochemical properties of enzymes and molecular motors can be directly probed with OT by optical forces This is achieved by biochemically tethering the optically trapped particle, often a microbead, to the biological system under study. Using the trapped particle as a handle, force can be detected from and transferred to the molecular system

Methods

Results

Conclusion