In this paper, we report on a printable glass-based manufacturing method and a new proof-of-concept colorimetric signal readout scheme for a dielectric barrier discharge (DBD)-type helium plasma photoionization detector. The sensor consists of a millimeter-sized glass chamber manufactured using a printable glass suspension. Plasma inside the chip is generated using a custom-built power supply (900 V and 83.6 kHz), and the detector uses ∼5 W of power. Our new detection scheme is based on detecting the change in the color of plasma after the introduction of target gases. The change in color is first captured by a smartphone camera as a video output. The recorded video is then processed and converted to an image light intensity vs retention time plot (gas chromatogram) using three standard color space models (red, green, blue (RGB), hue, saturation, lightness (HSL), and hue, saturation, value (HSV)) with RGB performing the best among the three models. We successfully detected three different categories of volatile organic compounds using our new detection scheme and a 30-m-long gas chromatography column: (1) straight-chain alkanes (n-pentane, n-hexane, n-heptane, n-octane, and n-nonane), (2) aromatics (benzene, toluene, and ethylbenzene), and (3) polar compounds (acetone, ethanol, and dichloromethane). The best limit of detection of 10 ng was achieved for benzene at room temperature. Additionally, the device showed excellent performance for different types of sample mixtures consisting of three and five compounds. Our new detector readout method combined with our ability to print complex glass structures provides a new research avenue to analyze complex gas mixtures and their components.

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In this paper, we present a new method for manufacturing millimeter-sized three-dimensional (3D) hemispherical resonators (HSRs) using a printable fused silica (FS) glass suspension. Our manufacturing process involves a combination of 3D printing, replication molding and casting steps to produce a complex FS-based HSR geometry. As proof of concept, we made a 9.5 mm-diameter and 0.5mm-thick resonator that was coated with thin films of chromium and gold (132nm). We tested the resonator using electrostatic actuation and detection methods and were able to detect a single resonance mode at 6.74 kHz with an experimental quality factor of approximately 1,540. This manufacturing method is easy to use and yields high results (greater than 95%), but it does require further optimization to improve device performance due to relatively high surface roughness.

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