This invention relates generally to the field of sensing devices and methods involving the detection of interfacial photo-voltages on an interfacial surface of a membrane or electrode to indicate the presence and amount of target chemical substances such as elements, compounds or molecules, both inorganic or organic within a solution, the photo-voltages being inter-atomic or inter-molecular. The devices and methods deal with interfacial charge transport where one medium making up the interface transmits electromagnetic radiation (IR through UV) and is simultaneously an electric conductor. More particularly, the invention relates to the field of devices and methods wherein particular photo-voltage active materials (PAMs) specific to the target chemical are deposited onto an electrode surface or a membrane and brought into contact with the target chemical analyte, wherein the PAMs generate interfacial photo-voltage electrical signals upon exposure to light, and wherein the difference in interfacial photo-voltages resulting from the presence of the target chemical relative to the expected photo-induced charge movements in the absence of the target chemical is analyzed to determine the presence of and the quantity of the target chemical present.
There are numerous instances where knowledge of the presence and quantity of a particular substance is required or desirable. Many qualitative and quantitative tests are known in the scientific arts. A number of these tests require either expensive equipment to analyze the test sample, analysis of the sample at a location remote from the sample collection location, or relatively long time periods to produce the result. It is an object of this invention to provide a device and a method which eliminates or reduces these drawbacks, where the detection and quantification of a target substance can be rapidly, accurately and relatively inexpensively achieved. As non-limiting examples, the invention may be used to detect and quantify metals including but not limited to Ac, Al, Ag, Am, Au, B, Ca, Cm, Co, Cr, Cu, Fe, Fl, Hf, I, In, K, Mg, Mn, Mo, Ni, Pa, Pb, Po, Pt, S, Th, Ti, U, Zn and Zr. Other target substances include but are not limited to dissolved gases, acid and alkaline phosphatases, dioxin, indole, nitrates, polysaccharides, sialomucins, skatole, sulfates, sulfomucins, trytophan, tyrosine, and uranic acid mucins. The invention can be used to detect the presence of and quantify particular strains of bacteria, viruses or other microorganisms, such as for example as a means to determine if water is sufficiently sanitized for drinking purposes. Bioreactors used to produce a wide range of products from brewers yeast to human insulin can be monitored. DNA, RNA, sugars and primary amines are other target substances which may be detected. Still other examples are illustrated in the disclosure to follow.