The fabrication and operation of a multi-analyte miniature conductance biosensor is described. The device responds to changes in the electrode double layer capacitance as the ionic strength is increased by the enzyme-catalysed generation of charged reaction products. Enzymes such as urease and l-asparaginase and a three-enzyme system consisting of urease, creatinase and creatininase were used to determine urea, l-asparagine and creatinine, respectively. Careful choice of suitable enzyme immobilization regimes led to device response times for the attainment of the steady state of the order of seconds. This fast response time allowed the construction of a flow cell with the incorporation of a urease-modified device for the continuous measurement of urea in flowing systems. © 1990.
