Direct writing of patterned functional electronic materials provides a new path to low cost and high throughput fabrication technology for producing integrated flexible circuits. However, it is equally important to assimilate printing technologies with solution based deposition steps in the same environment to attain a continuous and useful manufacturing process[1]. Direct patterning by inkjet printer have advantages of being low capitalization and equipment cost, high material efficiency (less than 5% of material gets wasted) and elimination of processes like photolithography[2]. Nevertheless, printed materials are characterized today by poor electrochemical performance due to i) residues of the ink binding materials on the surface of the printed circuits; ii) texture and morphologies (i.e. roughness, porosity); iii) surface impurities such as oxides. Therefore, currently, ink-jet printed electrodes have inferior biosensing properties compared to common negative printed electrodes where the metal is deposited by physical, chemical or electrochemical methods. A very realistic and simple approach to solve this issue is solution based deposition of noble catalytic metals on printed seed layer. This two-step process provides a relatively pure noble metallic high quality surface with good electrochemical properties for biosensing application. Moreover, this process is compatible with most solid and flexible substrates and fabrication processes.

A simple and efficient method has been developed to fabricate flexible, patterned gold (Au) biochip array. Micro-patterns of silver (Ag) ink were printed and dried on polyimide substrates. These micro patterns served as the activating seed layer for electrochemical Au deposition. Au deposition was carried out on Ag ink printed microchip array for various intervals of time to determine desired thickness. The thickness and conductivity measurements were performed. To investigate bio-electrochemical properties of the Au deposited chips, electrochemical impedance spectroscopy and cyclic voltammetry will be applied. The biosensing capabilities will be studied by the chronoamperometric method for different enzyme concentration.

Keywords: Inkjet printing, bio-electrochemical , Biochip array, Direct patterning.