A system and method for permitting a potential purchaser to review at least part of the subject matter of a document without being informed of the document’s bibliographic data and for assuring payment to a seller if the potential purchaser chooses to purchase the bibliographic data andor a copy of the original version of the document. The current sensor includes a housing having a Hall effect device and circuitry for transmitting a signal indicative of the current flowing through the electrical conductor. The microelectrode arrays have overall surface area and are electrochemically compatible with biological tissue. In some embodiments, the larger die is affixed to the support structure first and in other embodiments, the smaller die is affixed to the larger die first. The catalyst of the present invention is readily separated from polycarbonate and can repeatedly be used, and the above catalyst makes it possible to efficiently produce polycarbonate of a high quality without using harmful chlorine gas and phosgene and halogenated organic solvents such as dichloromethane and chloroform which are considered to exert an adverse effect on the environment.