基于微流控芯片的生物细胞电阻抗成像检测技术

Electrical Impedance Tomography for Biological Cell Sensing withMicrofluidic Device

基于多电极阵列微流控芯片通过仿真和试验的方法研究电阻抗成像检测技术(Microelectricalimpedancetomography,μEIT)在细胞检测方面的应用,并在微尺度两相流复杂的电气性能中探索重建细胞分布图像的最佳条件。在仿真分析中,对比了三种图像重构算法,其为广义矢量模式匹配法(Generalized vector sampled pattern matching, GVSPM)、Tikhonov正则化迭代法(Tikhonov regularization, TK)和投影Landweber迭代法(Projected landweber iteration, PLW)。仿真结果显示,GVSPM以最高的图像相关性I_C=0.84和最低的图像误差I_E=0.43被认为是本研究中的最佳图形重建算法。在试验研究中,用μEIT系统对酵母菌溶液中的细胞沉降进行了图像重建,试验结果显示,在频率f=1 MHz的情况下,所重建的图像具有最低的电压误差U_E=0.582,故可认为该溶液的最佳成像频率为f=1 MHz。最后,在频率f=1 MHz的情况下,对微流道的三个不同横截面用GVSPM重建细胞沉降图像,结果显示,各个截面的细胞浓度沿着流向下降,与以前研究中的各个截面上细胞浓度值(体积分数)Φ=17.5%下降至Φ=4.9%的结果一致。

A micro electrical impedance tomography(μEIT)system is developed to visualize cells concentration distribution inmicrochannel flow.Due to the complexity of electrical properties of theμEIT system in micro-scale measurement,simulation andexperiments are conducted to find the optimal conditions of the image reconstruction process.In the simulation,three imagereconstruction algorithms which are generalized vector sampled pattern matching(GVSPM),iterative tikhonov regularization(TK)and projected landweber iteration(PLW)are estimated,GVSPM is found to be the optimal algorithm for image reconstruction in thepresent study due to its higher image correlation I_C=0.84 and lower image error I_E=0.43.In the experiment,yeast cells and purifiedwater are employed as two-phase flow to measure the cells sedimentation in the microchannel at a range of frequencies with GVSPM,TK and PLW,respectively.The optimal frequency for theμEIT system is found as f=1 MHz due to its higher measurementsensitivity.GVSPM is found as the optimal image reconstruction algorithm because of its low voltage error U_E=0.582 and simplerimage reconstruction without regularization factor.Finally,images of cells sedimentation are reconstructed with GVSPM in threecross-sections in microchannel flow at f=1 MHz.The reconstructed images show that concentration of cells sedimentation from theupstream Z1 to downstream z5 is decreased gradually along the flow direction in the microchannel.