The effect of laser cutting on the Young’s modulus of Polydimethylsiloxane

Abstract

Laser cutting is often used in the fabrication of Polydimethylsiloxane (PDMS) substrates for novel microdevices such as wearable sensors and microfluidic devices. PDMS is a thermosetting polymer whose material properties are affected by the thermal conditions during the curing process. Since laser cutting exposes the cutting material to high temperatures, this might affect the heat-sensitive material properties. In this work, we examine how laser cutting affects the stiffness of PDMS by measuring the Young’s modulus of PDMS and comparing that to the Young’s modulus of laser-cut PDMS. We find an increase in the Young’s modulus from 0.34 to 0.37 MPa (9%) for PDMS mixed at a ratio of 20:1 base to curing agent. For 10:1 ratio PDMS, we find the increase in Young’s modulus is 31%, from 1.02 to 1.34 MPa.

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“…The Young's moduli are representative of an unloaded PDMS cornea at 0 mmHg. With a mixing ratio of 20:1 and varying baking temperatures and times, the Young's modulus of the material can be anywhere between 340 kPa to 500 kPa [23], [25], [26]. With a baking time of 2 hours at 80°C the Young's modulus can be estimated to be 400 kPa.…”