Study On Fabrication Of Microdevices On Polycarbonate Sheets By UV-patterning In Combination With Silver Activating

Recently, electroless deposition of metals on polymer surface has been widely used for metallization due to its simplification. Region-selective metalization of polymer surface has in recent years attracted increasing attentions due to the rapid development of microfluidic analytical systems and the microelectronics industry.The present work is aimed to fabricate integrated micro electrodes on polymeric microchips used for electrochemical detection.The thesis is composed of two parts:In chapter 1, the recent advances in both metallization of polymers and fabrication of metallic microdevices were reviewed.In chapter 2, a novel technique was established for region-selective metalization of polycarbonate (PC) surface by combining photoresist-free UV-patterning with silver activating and electroless gold plating. The surface of PC sheets was selectively exposed to the UV-lights emitted from a low pressure mercury lamp through a photo-mask, resulting in the photochemical generation of carboxyl groups on the UV-exposed region. The photochemically generated carboxyl groups could directly chemisorbe the silver ions. Upon the Ag~+-adsorbed PC sheet was immersed into an electroless gold plating bath, the adsorbed Ag~+ ions were quickly reduced to Ag~0 by the formaldehyde existing in the plating bath, and the aggregated silver nano-particles deposited on the UV-exposed region, forming the catalyst centre for the following electroless gold plating. Several analytical methods such as Attenuated total reflection Fourier transformation infrared spectrometer (ATR-FT-IR), X-ray photoelectron spectroscopy(XPS), atomic force microscope (AFM), scanning electron microscope (SEM) and cyclic voltammetry(CV) were used to characterize the modified PC surface. The formation of catalyst centre and the relative mechanism were studied. The electrochemical property of gold microelectrodes fabricated with this technique was detected and it is similar to that of gold disk electrode. When the prepared micro gold electrodes were demonstrated for amperometricdetection of hydrogen peroxide, high sensitivity was obtained compared to commercial standard gold microdisk electrode.The main novelty of the present work is summarized as:Developed a novel technique by combining photoresist-free UV-patterning with amine-free silver activating and electroless gold plating on PC sheet. Compared to previously related work, the approach for region-selective metalization of polycarbonate (PC) surface is simple, time-and cost-effective and could be easily industrialized.