A novel ion detector aiming at the homogeneous of drift gas

In standalone ion mobility spectrometry (IMS) instruments, the effect of drift gas turbulence reduces the sensitivity and resolution of the instrument. A traditional ion detector constructed with a Faraday plate and used to detect ions in an IMS is positioned at the end of the drift region. Drift gas flowing through this detector may introduce turbulence near the detector, possibly affecting the sensitivity and resolution of the device. To address this problem, a novel Faraday detector with a double layer structure was constructed. A number of dense and staggered holes were created on each layer of the detector. This design enabled the drift gas to pass through the holes of the detector, and the staggered nature of holes in the detector ensured that the ions could be detected. Theoretical simulations were conducted using the finite element method to obtain velocity distributions for both a standard Faraday detector and the modified Faraday detector. The results indicated that the novel ion detector created a homogenous gas under at high inlet flow rate while turbulence was still evident for the traditional Faraday detector. When the inlet flow rate was 1000 mL/min, the range of the unstable region of the drift gas in the axis of the drift tube with the novel ion detector was reduced by 97% relative to that for the traditional detector. The data suggests that due to such gains, sensitivity and resolution may be improved for standalone IMS instruments.