The Research Of Fabrication Process Of PMMA Electrospray Chip

Microfluid based lab on a chip, alternate name lab on a chip or microfluidic chip. The basic operation units involved in chemical and biological fields, such as sample preparation, reaction, separation, detection and cell culture, sorting and cracking, are integrated on a chip with several square centimeters (even smaller). Based on the network formed by micro channels, controllable fluid can run through the whole system. Therefore, microfluid based lab on a chip is a technology platform which can replace various functions of regular chemical or biological laboratory. Microfluidic chip has broad application prospects in medical, life science, drug development, chemical, food and environmental sanitation detection fields. Detection is an important function module of microfluidic chip. Regular microfluidic chip detectors include optical detection, electrochemical detection and mass spectrum detection. Mass spectrum detection includes electrospray ionization mass spectrometry (ESI) and matrix assisted laser desorption ionization (MALDI).In 1980s, two unique application fields challenged practical mass spectrometry technology:①analysis macromolecular compound;②supply effective interface between liquid chromatography and mass spectrometry urgently. In 1989, American scientist John B. Fenn applied electron spray ionization method on mass spectrometry technology firstly, which provided perfect solutions for two kinds of special requirements. Then, John B. Fenn got Nobel Prize in chemistry in 2002. Depending on the advantage of treating molecular protein, electron spray ionization method has obtained more and more attention.Based on MEMS process, Si mould has been fabricated. The relative merits of wet etching and dry etching have been compared. The process parameters of Si mould fabrication have been optimized. The hot embossing and bonding method is employed to fabricate PMMA electron spray ionization chip. Because micro channels of electron spray ionization chip should be fabricated on tip of PMMA chip, mould and PMMA chip should be aligned first during hot pressing process, and micro channels should be open. The tip of micro channel fabricated by traditional hot press method can not be filled up, closed channel can not be formed and capillary phenomenon does not appear. Meanwhile, depending on manual alignment, the relative position between micro channel and tip of PMMA chip can not be precise. To solve the problems above, a novel and simple fabrication method is presented in the paper. First, sharp angle trace is cut on PMMA chip by small current laser; Then, the manipulators are used to perform alignment operation under stereo vision microscope. After hot embossing and bonding, polymer PMMA electron spray ionization chip is fabricated successfully. The channel morphology and position both meet requirements. A simple test has been performed on the chip. The reagent is methanol solution (30%), the stable electron spray ionization forms. The relationship between onset voltage and distance between tip and plate, the relationship between electrospray voltage and loop current are measured.