# Maskless, Reusable Visible-Light Direct-Write Stamp for Microscale Surface Patterning

## TL;DR

A new method uses light and a reusable stamp to create detailed chemical patterns on surfaces without masks or harmful byproducts.

## Contribution

A maskless, reusable visible-light stamp for microscale patterning with photoacid and reversible activation.

## Key findings

- Line widths below 10 μm were achieved using photoacid in PDMS.
- The method is cost-efficient and avoids cytotoxic byproducts.
- The stamp can be reused for different patterns.

## Abstract

We report a straightforward method for creating large-area,
microscale
resolution patterns of functional amines on self-assembled monolayers
by the photoinduced local acidification of a flat elastomeric stamp
enriched with photoacid. The limited diffusivity of the photoactivated
merocyanine acid in poly(dimethylsiloxane) (PDMS) enabled to confine
efficient deprotection of N-tert-butyloxycarbonyl amino group (N-Boc) to line widths
below 10 μm. The experimental setup is very simple and is built
around the conventional HD-DVD optical pickup. The method allows cost-efficient,
maskless, large-area chemical patterning while avoiding potentially
cytotoxic photochemical reaction products. The activation of the embedded
photoacid occurs within the stamp upon illumination with the laser
beam and the process is fully reversible. Preliminary positive results
highlight the possibility of repeatable use of the same stamp for
the creation of different patterns.