Realisation of a biocompatible diffraction grating using an ArF excimer laser

Abdulsattar A Aesa,C D Walton

doi:10.1088/1757-899x/871/1/012058

Abdulsattar A Aesa, C D Walton

Open Access

https://doi.org/10.1088/1757-899x/871/1/012058

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Abstract

We report the fabrication of a bio-compatible diffraction grating made out chitosan, a derivative of chitin. The diffraction grating has been realised by laser ablation using 193 nm excimer laser. Thin spun coated chitosan films 520 nm thick were used in the laser ablation experiments. We report a laser ablation threshold for chitosan of FT = 85 ± 8 mJcm−2. A clean laser ablation process is observed with very little material redeposited on the sample. Following equipment; white light interferometry, scanning electron microscopy, power spectral density and Fraunhofer diffraction measurements were utilized to characterise the diffraction grating. Calculation of the temperature rise induced during laser ablation has been carried out and compared with decomposition temperatures deduced from thermogravimetric data. Applications of bio-compatible gratings realised by laser direct write patterning are briefly discussed.

Highlights

There is a great deal of interest in diffraction gratings made from bio-compatible materials within the scientific community
We report the fabrication of a bio-compatible diffraction grating made out chitosan, a derivative of chitin
We report using a laser direct write (LDW) method to fabricate surface relief grating

Summary

Introduction

There is a great deal of interest in diffraction gratings made from bio-compatible materials within the scientific community. The grating consisted of a thin taught wire formed around two fine pitch brass screws. It would appear the grating was not used for scientific purposes, Fraunhofer reproduced a similar grating in about 1813 using the first-ever ruling engine [1]. When an electromagnetic wave is an incident on a diffraction grating it will have its electric field amplitude, or phase, or both, modified. Both types of gratings have been fabricated by lasers for many years, as new material is developed new applications emerge. An area of specific interest in this work is the realisation of bio-compatible diffraction gratings for lab-on-chip (LOC) sensors

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