Signal processing in portable ion mobility spectroscopy

Ion mobility spectroscopy (IMS) is an analytical technique based on multi-disciplinary such as analytical chemistry, electronics, nuclear technique, etc. It is used to separate and identify ionized molecules in the gas phase based on their ion mobility in a carrier buffer gas. In recent years, explosives and drugs become an increasing security risk. Ion mobility spectroscopy (IMS) is a sensitive and low cost device that very suits for explosives and drugs detection, especially in the rapid field detection. We implemented the whole system on a dual-core board including a digital signal processor (DSP) and a microcontroller unit (MCU) for a home-made IMS instrument. Since the ion mobility spectroscopy (IMS) outputting signal is highly introduced with noise and background signals, fast signal processing to separate the spectrum signal from big noise and to locate the peaks in such an embedded system is the most important work for meeting the real-time field detecting requirement. In this paper, the signal acquisition, control and data processing such as digital filtering, de-noising, background subtraction, peak searching are discussed in details. Experimental results show that all true peaks were accurately located from high noised spectrum, and whole circle processing time was less than 25 ms, well satisfied system real-time requirement of 30 ms recurrence time.