Studying the ionic current activity in cells is useful in understanding the cell behavior, e.g. during wound healing and formation of embryos. Measuring the intracellular ion activities across the cell membrane is important in understanding cellular functions related to ion activities. A novel design using micro electrode arrays (MEA) for measuring ionic currents from cell membrane is presented here. The novel design of the electrodes enables the separation of the cells and the metal electrodes. This avoids cell contamination as there are no toxic chemicals produced at the cell surface by the electrode-cell-interaction. An electrically conducting medium (agar-agar) connects the cell to the electrode. The electrode has a layer of Ag/AgCl which is electrochemically deposited on patterned gold. The cells are suspended on top of a bio-compatible porous membrane in a medium. Soft-lithography technique is used to form the micro-fluidic channels made of Polydimethylsiloxane (PDMS) in which the electrolyte flows that connects cell and electrode. The cells are stimulated by a DC current generated using an agar bridge setup. Detailed fabrication of the MEA will be presented in this paper.

Microelectrode arrays (MEAs) are extensively being used to study the electrical properties of cells. Most of the MEAs use metal electrodes which are in direct contact with the cells. When using DC currents, this leads to undesirable chemical influencing of the cell. Also, metal electrodes are unsuitable for the measuring of constant potentials. A new kind of MEA is developed which replaces the metal electrodes by electrolyte-filled microchannels with Ag/AgCl-electrodes at their ends. The surface of the DCMEA consists of a nanoporous membrane that acts as a homogenous cell substrate, thus avoiding any topographical guidance of the cells. It is adhered to a polydimethylsiloxane layer with four electrode channels embedded in it, using a novel plasma bonding method. A transparent polymer ground plate connects the channels to the silver electrodes as shown in Fig. 1. This MEA allows for the stimulation of the cells with stationary, non-homogenous electric fields, e.g. to simulate the electrical environment near wounds in vitro. It has been proposed in the literature that intracellular ions are involved during cell migration. The DCMEA can be used to simulate in vitro electric fields to investigate intracellular ion changes. By loading cells with ion specific fluorescence dyes, real-time ion kinetic changes can directly be carried out on DCMEA. These studies will be performed by using a time lapse video microscope. In this paper we present the detailed fabrication and testing of the new DCMEA. Results on intracellular ion flows will be presented using this DCMEA.

In this paper we present a method for the integration of porous track‐membranes into silicone based microfluidic devices. It is based on a surface modification of the membranes which enables us bonding it to silicone using a glue‐free plasma bonding process. The membrane can be structured into permeable and impermeable regions on a sub‐10 μm scale. This is achieved by combining polymer imprinting with a layer transfer technique. The membrane is characterized and a direct current microelectrode array is presented as an application example. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A new kind of microelectrode array is presented that uses an arrangement of microfluidic channels filled with an electrolyte solution as electrodes. This allows for the spatially resolved, long term application of direct currents to cells in a culture medium on the chip. A crucial task in the production of the chip is the integration of a nanoporous polymer membrane that acts as a basis for cell adhesion and as a support for the layer that contains the microelectrode openings.