基于微机电系统(MEMS)技术,研制了一种微型高场非对称波形离子迁移谱(FAIMS)传感器芯片.芯片尺寸为18.8mm×12.4mm×1.2mm,由离子化区、迁移区、离子检测区组成.采用真空紫外灯离子源在大气压环境下对样品进行离子化,经过离子化区中聚焦电极的电场作用,实现离子在进入迁移区之前的聚焦,提高离子信号的强度.通过在上下玻璃上溅射Au/Cr(300nm/30nm)金属,并与厚度为200μm、采用感应耦合等离子体(ICP)工艺刻蚀的硅片键合,形成迁移区的矩形通道,尺寸为10mm×5mm×0.2mm.离子检测区为三排直径200μm、间距100μm交错排列的圆柱阵列式微法拉第筒,能同时检测正负离子.采用频率为2MHz,最大电压为364V,占空比为30%的高场非对称方波电压进行FAIMS芯片实验.以丙酮和甲苯为实验样品,载气流速80L·h^-1,补偿电压从-10V到3V以0.1V的步长进行扫描,得到了丙酮和甲苯的FAIMS谱图,验证了FAIMS芯片的性能.丙酮和甲苯的FAIMS-MS实验进一步表明FAIMS系统实现了离子分离和过滤功能.
Based on micro-electro-mechanical system(MEMS) technology,a miniature high-field asymmetric waveform ion mobility spectrometry(FAIMS) sensor chip was designed and fabricated.The chip's dimensions are 18.8 mm×12.4 mm×1.2 mm.It consists of an ionization region,a drift tube,and an ion detection region.In the ionization region,the sample is ionized by a vacuum ultraviolet ion source at ambient pressure.The produced ions were then focused before entering the drift tube under the influence of the electrical field created by the focusing electrodes in the ionization region,which increased the ion signal intensity.A 200 μm thick silicon wafer was etched by inductively coupled plasma(ICP) and then bonded together with two glass plates sputtered with Au/Cr(300 nm/30 nm) to form a rectangular drift tube with dimensions of 10 mm×5 mm×0.2 mm.The ion detection region is a micro Faraday cup,which is made up of three rows of staggered cylinders of 200 μm in diameter and with a 100 μm spacing interval.The Faraday cup can detect positive and negative ions simultaneously.The FAIMS chip was investigated using high-field asymmetric rectangular waveform power with a peak voltage of 364 V at a frequency of 2 MHz and a duty cycle of 30%.Acetone and toluene samples were used to characterize the sensor chip.With a carrier gas flow rate of 80 L·h-1 and by sweeping the compensation voltage from-10 to 3 V at a 0.1 V steps,acetone and toluene spectra were obtained.The FAIMS-MS experiments further show that ions can be separated and filtered by the FAIMS system.