Material Characteristics and Laser Bonding for Microfluidics

What is microfluidic chip technology? Microfluidic technology is based on microchannels as a network, and integrates various analytical equipment with optical, electrical and liquid transmission functions such as micropumps, microvalves, microreservoirs, microelectrodes, and microdetection elements to the maximum extent possible on the chip, integrating various analytical equipment such as collection, dilution, reagent addition, reaction, separation, and detectors. The size of the current microfluidic chip is about a few square centimeters, and the width and depth (height) of the microfluidic channel are micrometers and submicrometers, respectively.

While the processing technology of microfluidics originated from the microprocessing of semiconductor chips and integrated circuit chips, they are different from the integrated circuit chip technology that mainly processes two-dimensional and shallow depth silicon materials. In recent years, the research on chip materials and processing technology based on microfluidic chips has gradually received attention from many developed countries.

So what materials and characteristics do microfluidic chips use?

What materials are used in microfluidic chips?

Rigid materials:

Single crystal silicon, amorphous silicon, glass, quartz, etc.; Rigid organic polymer materials such as epoxy, polyurea, polyamine, polystyrene and polymethyl methacrylate, etc.;

Elastic materials:

Dimethylsiloxane (PDMS).

There are many process procedures and technologies for microporous chips, such as mask preparation, wet etching, microfabrication, soft etching, microcontact printing, organic polymer molding, hot pressing, laser cutting, LIGA technology, sealing technology, etc. Among them, laser etching uses ultraviolet laser to expose degradable polymer materials, which can accurately replicate the two-dimensional geometric figures on the film. The photolysis depth of the material is controlled by adjusting the exposure intensity. The degradation products are removed by pressure cleaning to obtain a substrate with microchannels. Thermal bonding with another cover sheet with holes can obtain the required chip.

This method has high requirements for equipment and technology, but the steps are simple, there is no ultra-clean environment, and the precision is high. It is suitable for microporous processing on the surface of photodegradable polymers such as polymethyl methacrylate and polycarbonate.