School of Electronic and Information Engineering, Soochow University, Suzhou 215006, China.
Sensors (Basel). 2022 Jun 27;22(13):4866. doi: 10.3390/s22134866.
Drift-time ion mobility spectrometer (DT-IMS) is a promising technology for gas detection and analysis in the form of miniaturized instrument. Analytes may exist in the form of positively or negatively charged ions according to their chemical composition and ionization condition, and therefore require both polarity of electric field for the detection. In this work the polarity switching of a drift-time ion mobility spectrometer based on a direct current (DC) corona discharge ionization source was investigated, with novel solutions for both the control of ion shutter and the stabilization of aperture grid. The drift field is established by employing a switchable high voltage power supply and a serial of voltage regulator diode, with optocouplers to drive the ion shutter when the polarity is switched. The potential of aperture grid is stabilized during the polarity switching by the use of four diodes to avoid unnecessary charging cycle of the aperture grid capacitor. Based on the proposed techniques, the developed DT-IMS with 50 mm drift path is able to switch its polarity in 10 ms and acquire mobility spectrum after 10 ms of stabilization. Coupled with a thermal desorption sampler, limit of detection (LoD) of 0.1 ng was achieved for ketamine and TNT. Extra benefits include single calibration substance for both polarities and largely simplified pneumatic design, together with the reduction of second drift tube and its accessories. This work paved the way towards further miniaturization of DT-IMS without compromise of performance.
漂移时间离子迁移谱仪（DT-IMS）是一种很有前途的气体检测和分析技术，可制成小型仪器。根据其化学成分和电离条件，分析物可能以正离子或负离子的形式存在，因此需要电场的两个极性进行检测。在这项工作中，研究了基于直流（DC）电晕放电电离源的漂移时间离子迁移谱仪的极性切换，提出了用于离子快门控制和孔径格栅稳定的新颖解决方案。通过使用可切换的高压电源和一系列稳压器二极管来建立漂移场，并在极性切换时使用光电耦合器驱动离子快门。通过使用四个二极管在极性切换期间稳定孔径格栅的电势，避免了孔径格栅电容器的不必要充电循环。基于提出的技术，开发了具有 50mm 漂移路径的 DT-IMS，能够在 10ms 内切换极性，并在 10ms 的稳定时间后获得迁移谱。与热解吸采样器耦合，可实现对氯胺酮和 TNT 的检测限（LoD）为 0.1ng。额外的好处包括两个极性都使用单一的校准物质，以及简化了气动设计，减少了第二漂移管及其附件。这项工作为进一步实现 DT-IMS 的小型化铺平了道路，而不会影响性能。
