TECH | FOCUS
Glass Molding Produces Microfluidic Devices for Mass Production
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he joint development of Panasonic Corporation and Institute of Microchemical Technology Co., Ltd. (IMT) has resulted in the discovery of a mass-production technology of microfluidic devices using glass molding. A microfluidic device can perform various chemical processes (mixing, reaction, extraction, synthesis, detection) in a minute flow path with a small amount and high efficiency by flowing liquid through a groove with a width and depth of several hundreds of micrometers. Compared to the conventional glass etching method, this technology realizes low-cost and highly accurate mass production. These devices can be applied to sensing and analysis for medical, biological, environmental (water and air quality) applications, among others.Conventional glass microfluidic devices have not been widely used due to high cost and poor precision. This latest development has achieved mass production and cost reduction of glass microfluidic devices by combining IMT’s microfluidic device design technology and Panasonic’s glass molding technology. As a result, the disposable use of glass microfluidic devices becomes possible. In addition, by realizing high precision, it is easy to incorporate the device as part of equipment and systems.

By taking advantage of the environmental and chemical resistance of glass microfluidic devices, it can be applied to environmental sensing, blood testing, and pharmaceutical equipment as disposable detection devices for analysis and testing in outdoor and harsh environments.

Employed Technologies
The newly developed microfluidic device has dimensions of up to φ50mm. Production capacity can reach more than 10,000 devices per month using a manufacturing process with the shape precision of about 1µm.

In the development of this technology, the research group has employed the following: 1) Design and interface technology of microfluidic device optimized for glass molding; 2) Microstructure mold processing technology to higher hardness material and microstructural glass molding technology to precisely transfer to glass; and 3) Thermal bonding technology to join a flat glass plate and a plate with microstructures.

Fig. 1: Image of microfluidic technology
Fig. 1: Image of microfluidic technology
Fig. 2: Glass molding technology
Fig. 2: Glass molding technology (mold machining technology, mold protection coating technology, molding technology)

Technology Background
A general microfluidic device made of glass used in microfluidics technology (Fig. 1) is mainly produced by etching techniques. After drawing the flow path pattern by photolithography, the glass flow path is formed by etching, and the cover glass with the machined introduction hole is bonded. Since the inception of this field, IMT, as a pioneer in the planning, design, and manufacture of glass microfluidic devices, has provided high-level products. However, in addition to the skill required for manual manufacturing, the manufacturing process took several months. For this reason, the manufacturing time and cost per piece became a hurdle, and generalization and industrial mounting were not realized, and the use was limited mainly to basic research applications.

On the other hand, Panasonic has been developing and manufacturing glass molding technology since the 1980s, and has contributed to the commercialization of the world’s highest level of optical devices, which are used in lenses for various optical devices, like digital still cameras.

By combining Panasonic’s glass molding technology and IMT’s design technology, it became possible to develop microstructure mold machining technology, molding technology, and joining technology suitable for mass production of microfluidic devices using glass molding technology (Fig. 2). The companies have succeeded in developing a mass production technology for microfluidic devices. As a result, it is possible to reduce the cost to about 1/10 compared to conventional manufacturing method, and to supply glass microfluidic devices with improved precision 10 times or more in less than half the delivery time.

With the development of mass production technology for microfluidic devices using this glass molding technology, glass microfluidic devices are now widely used as disposable detection devices for analysis and testing in outdoor and harsh environments, and for disposable blood testing equipment devices.

1) Water quality inspection device
1) Water quality inspection device
 3) Genetic testing device
3) Genetic testing device
3: Application samples of microfluidic devices using glass molding technology
2) General-purpose device

Fig. 3: Application samples of microfluidic devices using glass molding technology

Microfluidic Device Technology
The microfluidic device technology integrates chemical processes, such as mixing, reaction, separation, extraction, synthesis, and detection in a flow channel of several tens to several hundreds of micrometers created on a substrate (microfluidic device) of several centimeter square. By freely integrating chemical processes that have been performed in laboratories and factories in the microspace of microfluidic devices, it becomes possible to use energy and space much more efficiently. It is expected to contribute greatly to the evolution of chemical technology in the future. This chemical process integration technology (microfluidic technology) in the micro space was established as a result of research and development of the Kitamori “Integrated Chemistry” project. The project was carried out at Kitamori Lab., Department of Applied Chemistry, School of Engineering, The University of Tokyo, and Kanagawa Academy of Science and Technology (currently Kanagawa Institute of Industrial Science and Technology).