Development of an electrochemical biosensor array for quantitative polymerase chain reaction utilizing three-metal printed circuit board technology

• We have developed a method to produce arrays of electrochemical biosensors and heaters using a three-metal printed circuit board technology.
• The electrochemical performance and surface morphology of the biosensor microelectrodes were characterized and evaluated.
• The electrochemical biosensors and heaters were demonstrated for quantitative polymerase chain reactions, performed with 95% PCR efficiency.

A compact biosensing system is presented that contains an array of devices composed of three-microelectrode electrochemical sensors and resistive heaters. The devices are intended for employment in quantitative polymerase chain reactions in multiple chambers that can be controlled via microcontroller. Arrays of sensors and heaters were developed using an inexpensive advanced printed circuit board technology featuring three different metals. The three-microelectrode sensors were fabricated by a new series of photolithographic and electroless plating processes. The surface morphology of the microelectrodes was characterized by several imaging techniques, including scanning electron microscopy and atomic force microscopy. The electrochemical properties of the microelectrodes were studied by cyclic voltammetry in order to estimate the active electrochemical surface area by solving the Randles–Sevcik equation. The on-board thermal cyclers were realized by feedback control embedded in a portable microcontroller. Quantitative polymerase chain reactions with methylene blue as the redox indicator were carried out as an example of biosensing with the proposed devices, and the results indicate that the prototype array is able to serve as an inexpensive, practical platform for mass production of portable point-of-care instrumentation containing arrays of addressable heaters and sensors.