A MEMS radio-frequency ion mobility spectrometer for chemical vapor detection

• Published in: Sensors and actuators. A, Physical Vol. 91; no. 3; pp. 301 - 312
• Main Authors: Miller, Raanan A., Nazarov, Erkinjon G., Eiceman, Gary A., Thomas King, A.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 15.07.2001; Elsevier Science
• Subjects: Applied sciences; Chemical detector; Electron, ion spectrometers and related techniques; Exact sciences and technology; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Ion mobility spectrometer; Mechanical engineering. Machine design; MEMS; Physics; Precision engineering, watch making; Radio-frequency spectrometer; rf-IMS; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Chemical detector; Ion mobility spectrometer; MEMS; Radio-frequency spectrometer; rf-IMS; Micromechanical devices; Electromechanical device; Ion mobility; Atmospheric pressure; Gas flow; Chemical sensor; Experimental study; Radiofrequency; Spectrometer; Chemical ionization
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/S0924-4247(01)00600-8

A first-of-a-kind micro-electro-mechanical systems (MEMS) radio-frequency ion mobility spectrometer (rf-IMS) with a miniature drift tube of total volume 0.6 cm 3 has been fabricated and tested. The spectrometer has detection limits in the parts per billion (ppb) and the ability to identify chemicals such as isomers of xylene not resolved in conventional time-of-flight ion mobility spectrometry. Spectrometer operation with a miniature 10.6 eV ( λ=116.5 nm) UV photodischarge lamp and a 1 μCi radioactive ionization source has been demonstrated. The resultant spectra with both these ionization sources are similar, with several additional peaks evident for the radioactive source. The effect of varying the carrier gas flow rate on the resultant spectra has been investigated and optimal flow conditions are found at flow rates between 2 and 3 l/min. The rf-IMS has been interfaced to a mass spectrometer (MS) and rf-IMS spectral peaks have been confirmed. The rf-IMS/MS configuration illustrates another use for the rf-IMS as a pre-filter for atmospheric pressure chemical ionization (APCI) mass spectrometry applications.