An emailfax communication system is disclosed for use in a packet switching network environment including a mail server for storing email messages for transmission thereof, in the form of a fax document, to one or more recipient fax machines. The transistor T1 transfers the electric charge generated by the photodiode PD to the first capacitance section C1. The over-current protection circuit may sense an over-current condition at the load and truncate the drive signal in response to the over-current condition. The ion exchange membranes may be configured to provide a ratio of a pH of the concentrate stream and a pH of the dilution stream to be less than about 1. With this configuration, the degree of optical separation and image forming efficiency of an illumination light is improved. In particular, the present invention relates to planar polymer electrodes for making patch clamp measurements of ionic currents through biological membranes, such as the plasma membranes of living cells.