A Novel DC Microplasma Sensor Constructed in a Cavity PDMS Chamber with Needle Electrodes for Fast Detection of Methanol-containing Spirit

A novel microplasma device, for the first time, was constructed in a cavity Poly (dimethylsiloxane) (PDMS) chamber with two normal syringe needles serve as both the gas channels and the electrodes. This device employs argon plasma with direct current for molecular fragmentation and excitation. The microplasma is generated at atmospheric pressure in the PDMS chamber of 0.5 mL (5 × 10 × 10 mm(3)) volume with a sealable plug. Since the microplasma is maintained in a chamber by separation of the discharge zone and the substrate, stability for a long time of the microplasma is realized which could be observed by argon background emission fluctuation and SEM characterization. This property is beneficial for spectrometric detection of many volatile organics in this chamber. Besides, this kind of microplasma sensor has advantages such as flexibility in replacement of electrodes, convenience in clearance of the discharge chamber, small instrument volume, simple structure, and ease of operation. In addition, methanol-containing spirit samples were chosen to estimate the detecting performance of this microplasma for volatile organic compounds (VOCs) analysis by molecular emission spectrometry. Significant differences are observed upon the introduction of the spirit and the methanol-containing spirit samples. A detection limit of 0.3% is obtained on this microplasma device.