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

（1）利用抗原-抗体反应的选择性DEPIM（介电电泳阻抗测量）-测试DEPIM与免疫测定的两种组合。在一种方法中，采用细菌的凝集来增加介电泳力。另一种方法利用固定在微电极表面上的抗体分子。这两种方法都可以在初步介电电泳富集后在电极表面留下特异性细菌。凝集或固定的细菌可以通过电极电导的剩余增加来电检测。（2）用于回收和富集细菌的介电电泳过滤器-使用多段DEP过滤器在1小时内将细菌悬浮液富集30倍。DEP过滤富集成功地与DEPIM结合，用于在较低密度下进行细菌检测，作为预富集程序。（3）使用电透化的高灵敏度DEPIM-通过向捕获的细菌施加高交流电场，观察到电导突然增加，这可能是由电透化引起的。对于酵母细胞，DEPIM灵敏度的下限从10^4 CFU/ml提高到10^2 CFU/ml，诊断时间为15分钟。（4）碳纳米管的介电泳操纵及气敏应用--碳纳米管在正介电泳力的作用下被捕获并富集在微电极间隙中。在DEP捕获过程中，电极阻抗随着CNT数量的增加而变化。保留碳纳米管的微电极可以检测浓度低于10 ppm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.