Metallic Glass Used to Make 'Lab-on-a-Chip' Parts Cheaper

Metallic Glass is a generic name for disorganized metal alloys (combinations of metals). The disorganized structure of the atoms in metallic glasses gives them the strength and durability of metals, but they can be used to make teeny-tiny molds to make plastic parts, a feat traditional metals can't do.

Using these metallic glasses with new manufacturing technology allows researchers to mass produce components for next-generation computer storage devices and disposable medical and chemical test kits cheaply.

"Our technology is a new process for mass producing high-value polymer components, on the micrometer and nanometer-scale," study researcher Michael Gilchrist, of University College Dublin, in Ireland. "This is a process by which high-volume quantities of plastic components can be mass produced with one hundred times more precision, for costs that are at least ten times cheaper than currently possible."

The study will be published in the May issue of the journal Materials Today. 

The researchers are using materials called "bulk" metallic glasses to produce high-precision molds for making tiny plastic components. The components, with detailed microscopically patterned surfaces could be used in the next generation of computer memory devices and medical testing kits and chemical reactors with tiny parts.

Bulk metallic glasses are a type of metal alloy, but instead of having a regular, crystalline structure like an everyday metal such as iron or an alloy like bronze, the material's atoms are arranged haphazardly. This disordered atomic structure is similar to the structure of the silicon and oxygen atoms in the glass we use for windows and drinking vessels, hence the name.

The haphazard arrangement of atoms in metallic glasses means that they have some very different mechanical properties from conventional metals. They can be heated and molded like plastics and they can be machined with microscopic precision to a smaller scale than traditional metals. They also retain the strength and durability of normal metals.

The researchers have now exploited the haphazard nature of the atoms in metallic glasses to allow them to machine microscopic features in the metal. This is not possible with conventional metals such as tool steel used in molds which cannot typically be machined with better than 10 micrometers (about the width of a cotton fiber or a human red blood cell) precision because of its crystalline grain structure. They have then used the resulting strong and durable metallic devices to carry out injection molding of plastic components with microscopic surface patterns.

The research team explains that with their injection molding equipment it is now possible to create millimeter-sized polymer components that have surface features of a similar size to human cells at 10 micrometers or even the smallest viruses at less than 100 nanometers. The new manufacturing process could thus allow ‘lab-on-a-chip’ devices to be constructed that could handle and test samples containing single cells and viruses or large biomolecules including DNA and proteins.

"These precision plastic parts are the high value components of microfluidic devices, lab-on-chip diagnostic devices," Gilchrist said.

Once the technology is extended to the tens of nanometers length scale, the team suggests that it could be used to make high-volume, low-cost, information storage systems. The team is currently optimizing their technology with this goal in mind.

"The worldwide trend of miniaturization means that these devices and components are getting progressively smaller and smaller; the problem faced by today’s technologies is that they will soon be unable to manufacture at these smaller dimensions at competitive prices," The researchers write. "If you just consider the microfluidic devices market without the biological content: this is forecast to reach $5 billion by 2016."