Bonding solutions for microfluidic chips and complex flow channels - plastic laser welding

With the improvement of quality over time, people's requirements for life and medical security are getting higher and higher. Major medical device companies have invested more and more in the research and development of medical devices, and the production technology of medical devices has been continuously improved. The huge financial support has prompted many of the latest technologies to be applied to the production of medical devices.

Plastic laser welding process is a new type of plastic welding process that emerged in the 1990s. This process is a non-contact welding method that does not generate vibration, noise and dust during the welding process. This is a very clean precision welding method, which is very suitable for the precision welding of medical plastic products.

During the plastic laser welding process, laser light of a specific wavelength is emitted from the laser head, penetrates the upper plastic of the workpiece to be welded, and is absorbed by the lower plastic surface of the workpiece. After the lower plastic surface melts, the heat is transferred to the lower surface of the upper plastic and begins to melt. Under the pressure of the fixture, the melted parts are welded together and form a strong weld after cooling.

Microfluidic Chip

The microfluidic chip integrates the sample preparation, biochemical reaction and result detection steps into a very small plastic-based chip, so that the amount of reagents used for detection becomes micro-level, or even nano- or skin-level. In addition to using a small amount of reagents, the microfluidic chip also has the advantages of fast reaction speed and disposable.

The microfluidic chip is a project that has been vigorously developed in China in recent years. The microfluidic chip is actually a micro-diagnostic platform that can quickly diagnose diseases and save a lot of manpower and material resources. At the same time, the microfluidic chip diagnostic platform is easy to carry and is suitable for the rapid diagnosis of diseases in underdeveloped or remote areas. Microfluidic chips are easy to use, but it is not easy to produce microfluidic chips.

The microfluidic chip consists of a cover sheet and a glass sheet. The cover is a plastic film or a plastic film with a thickness of several millimeters; many complex precision channels are formed on the glass by engraving or injection molding, and the width of the channel is generally around 100 microns to 1 millimeter. In order to seal these precision channels, the usual processes mainly include ultrasonic, hot pressing and gluing processes, all of which have fatal defects. The ultrasonic process will generate a large amount of overflow and dust, destroying and polluting the channel; the hot pressing process has a large heat-affected area, which is easy to deform and overflow, destroying the channel structure, and the hot pressing process has low production efficiency; glue bonding will cause glue to enter the channel and pollute the channel. At the same time, production requires the addition of glue dispensing and glue curing processes, which increases costs. In order to solve the above problems, the most reliable process is plastic laser welding process. The laser welding process of microfluidic chips is mainly a covering welding process.

The mask welding process uses a linear laser beam, and the mask partially shields the flow channel. When the laser beam scans the chip, the part that needs to be welded is welded, and the flow channel will not be affected because the mask will block the laser. The welding accuracy of mask welding (wire edge to flow channel) can reach 0.1mm. This accuracy can meet the requirements of most clinical microfluidic chips.

Plastic laser weldingThe upper and lower workpieces to be welded must be clamped with a fixture. The purpose of using a fixture is to make the welding surfaces of the upper and lower workpieces to be welded fit closely. For large-area workpieces, it is difficult to use a fixture to ensure that the welding surface fits closely due to the inevitable deformation or uneven surface of the injection molded parts. We have rich experience in this area for reference.