Gas Sensor – Liquid Crystals, Holography, Metasurfaces

Researchers have developed a compact gas sensor platform that combines liquid crystals (LCs) with holographic metasurfaces to sense a volatile gas promptly and provide instantaneous feedback through a visual holographic alarm. This technology integrates the advantages of the stimuli responsiveness of LCs and the compactness of metasurfaces while maximizing the effectiveness of the sensor by providing gas-sensing information through a visual holographic alarm without the need for any further complex instrumentation.

The metasurface hologram (or metahologram) is made of hydrogenated amorphous silicon (a-Si: H) and is designed to reproduce different holographic images according to the polarization of incident light and maximizes the polarization conversion efficiency by simultaneously using the geometric and propagation phase of each nanostructure.

The wearable and ultracompact holographic gas sensor could be a vital platform to prevent gas poisoning accidents in various working and military environments by simply mounting the sensor onto the gloves or glasses of the user, giving them a prompt visual warning through the holographic alarms.

They developed ultracompact gas sensors without additional complex instruments or machinery to report the visual information of gas detection by combining the advantage of rapid responses to gases realized by LCs with the compactness of holographic metasurfaces. They demonstrate a metasurface-integrated gas sensor on safety goggles via a one-step nanocasting process that is attachable to flat, curved, and flexible surfaces to demonstrate the applicability of the compact sensors.

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