Rapid, non-contact identification of organic solvents: Monolithic GaN chips incorporating PDMS/PS photonic crystals

Abstract

<p>The prompt identification of organic solvents is essential in many practical scenarios. This work introduces a compact optical device for rapid, non-contact detection of organic solvents. The fabrication of the GaN chip employs a monolithic integration approach, enabling the simultaneous formation of on-chip components responsible for light emission and light detection. The self-assembled polystyrene (PS) spheres embedded in a polydimethylsiloxane (PDMS) layer as photonic crystals can effectively induce distinct optical changes when exposed to organic solvents. By analyzing the magnitude and recovery time of the photocurrent signals, up to seven types of organic samples can be distinguished. Different from traditional optical sensing systems, the proposed chip-level integration strategy eliminates the need for external assembly of optical components, resulting in an ultracompact millimeter-sized sensing unit. The developed device also offers features of simplicity of use and a short measurement time of less than 10 s, making it a feasible solution for quick detection in emergency scenarios.</p>