Selective bacteria detection using dielectrophoretic impedance measurement combined with antigen-antibody reaction

(1)利用抗原-抗体反应进行选择性介电阻抗测量--对DEPIM与免疫测定法的两种组合进行了试验。在一种方法中，利用细菌的凝集作用来增加介电泳力。另一种方法是将抗体分子固定在微电极表面。-这两种方法都可以在初步的介电泳富集后在电极表面留下特殊的细菌。可以通过电极电导的残余增加来检测凝集或固定化的细菌。(2)用于细菌恢复和浓缩的介电泳滤器-使用多段DEP过滤器在一小时内将细菌悬浮液浓缩30倍。-DEP过滤器浓缩与DEPIM成功地结合用于低密度的细菌检测作为预富集程序。(3)使用电渗透的高灵敏度DEPIM-通过对捕获的细菌施加高交流电场，观察到可能由电渗透引起的电导突然增加。-对于酵母细胞，DEPIM的灵敏度下限从104 cfu/ml提高到10 2cfu/ml，诊断时间为15min。(4)碳纳米管的介电操作和气体传感器的应用-碳纳米管在正的DEP力的作用下被捕获并富集在微电极缝隙中。在DEP捕获过程中，电极阻抗随碳纳米管数量的增加而变化。-保留碳纳米管的微电极可以检测到浓度低于10ppm的氨气。

(1)Selective DEPIM (dielectrophoretic impedance measurement) using antigen-antibody reaction-Two kinds of combinations of DEPIM with immunoassay are tested. In one method, agglutination of bacteria is employed to increase dielectrophoretic force. The other method utilizes antibody molecules immobilized onto the microelectrode surface.-Both methods can leave peculiar bacteria on the electrode surface after preliminary dielectrophoretic enrichment. Agglutinated or immobilized bacteria can be electrically detected by residual increase of the electrode conductance.(2)Dielectrophoretic filter for recovery and enrichment of bacteria-The bacteria suspension was enriched by 30 times in one hour using a multi-segment DEP filter.-The DEP filter enrichment was successfully combined with DEPIM for bacteria detection at lower density as a pre-enrichment procedure.(3)High sensitive DEPIM using electropermeabilization-By applying high ac electric field to the trapped bacteria, abrupt conductance increase, which is possibly caused by electropermeabilization, is observed.-For yeast cells, the lower limit of DEPIM sensitivity is improved from 10^4 to 10^2 CFU/ml for 15 min diagnosis time.(4)Dielectrophoretic manipulation of carbon nanotubes and gas sensor application-Carbon nanotubes (CNTs) were trapped and enriched in an microelectrode gap under the action of a positive DEP force. During the DEP trapping, the electrode impedance varied as the number of CNTs increased.-The microelectrode retaining the CNTs could detect ammonia gas below 10 ppm concentration.