High sensitive detection of biological cells using dielectrophoretic impedance measurement method combined with electropermeabilization

This paper describes a detection method of biological cells or bacteria by using a dielectrophoretic impedance measurement (DEPIM) method combined with electropermeabilization. The authors have previously proposed a bacteria detection technique called DEPIM method, using positive dielectrophoretic force to capture bacteria in suspension onto an interdigitated microelectrode array. DEPIM could realize selective bacteria inspection according to their viability or species. In this paper, the authors propose a new method to improve the DEPIM sensitivity using electropermeabilization phenomenon. In the conventional DEPIM, bacteria were detected by measuring electrical conductance of intact cells captured onto a microelectrode by dielectrophoresis (DEP). In the proposed method, electropermeabilization is performed after the dielectrophoretic cell trap in order to release intracellular ion. 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 DEPIM signal is boosted by two orders of magnitude relative to the conventional DEPIM. Consequently, the lower limit of DEPIM sensitivity is improved from 104 to 10(2) CFU/mI for 15 min diagnosis time. (C) 2003 Elsevier B.V. All rights reserved.