An Integrated Microfabricated Chip with Double Functions as an Ion Source and Air Pump Based on LIGA Technology

Abstract

The injection and ionization of volatile organic compounds (VOA) by an integrated chip is experimentally analyzed in this paper. The integrated chip consists of a needle-to-cylinder electrode mounting on the Polymethyl Methacrylate (PMMA) substrate. The needle-to-cylinder electrode is designed and fabricated by Lithographie, Galvanoformung and Abformung (LIGA) technology. In this paper, the needle is connected to a negative power supply of −5 kV and used as the cathode; the cylinder electrodes are composed of two arrays of cylinders and serve as the anode. The ionic wind is produced based on corona and glow discharges of needle-to-cylinder electrodes. The experimental setup is designed to observe the properties of the needle-to-cylinder discharge and prove its functions as an ion source and air pump. In summary, the main results are as follows: (1) the ionic wind velocity produced by the chip is about 0.79 m/s at an applied voltage of −3300 V; (2) acetic acid and ammonia water can be injected through the chip, which is proved by pH test paper; and (3) the current measured by a Faraday cup is about 10 pA for acetic acid and ammonia with an applied voltage of −3185 V. The integrated chip is promising for portable analytical instruments, such as ion mobility spectrometry (IMS), field asymmetric ion mobility spectrometry (FAIMS), and mass spectrometry (MS).

Design, Fabrication and Mass-spectrometric Studies of a Micro Ion Source for High-Field Asymmetric Waveform Ion Mobility Spectrometry

“…This demonstrated that the gas jet does not have an obvious effect on the discharge current. In contrast to Figure 6b of [23], it shows different characteristics. In Figure 6b, there are corona and glow discharges, apparently, when there is no gas flow.…”

“…The microchip works at ambient pressure and room temperature both with and without a N 2 supply. First, the discharge starts when N 2 is not supplied, which has been described in detail [23]. There were corona and glow discharges with the discharge voltage increasing from −3050 V to −3563 V.…”

“…Figure 6a shows the discharge characteristic of the ion source when the gas flow velocity is varied. Figure 6b concerns the discharge characteristic of the ion source without gas flow (see [23]). There are interesting findings when comparing our results with those found in [23].…”

“…Figure 6b concerns the discharge characteristic of the ion source without gas flow (see [23]). There are interesting findings when comparing our results with those found in [23]. The discharge current is almost the same under different N 2 supply speeds, as shown in Figure 6a.…”

“…The fabrication process of the micro ion source has been described previously [23]. The needle and cylinder electrodes were fabricated by copper electroplating using LIGA (lithographie, galvanoformung and abformung) technology.…”