When thinking about microfabrication, materials such as alloys, metals, and plastic likely come to mind, However, it was glass and silicon from which the first microfluidic devices were created. Glass micromachining has many advantages and a wide range of applications.

In this post, we will compare three glass microfabrication techniques that it possible to transform glass into microfluidic devices. We’ll examine surface micromachining, buried channel techniques, and bulk micromachining.

Surface Micromachining

The surface micromachining technique consists of the use of a sacrificial layer which is shaped to define the desired fluid channels, then a structural layer is deposited and finally the sacrificial layer is etched. It should be noted that although surface micromachining offers greater potential for the fabrication of multilayer devices compared to mass micromachining, it nevertheless involves more process steps per layer. Surface micromachining is particularly interesting for the fabrication of nano-channels. Indeed, the thickness of the sacrificial layer that corresponds to the final height of the channel can easily be controlled to the nearest nanometer. Bulk micromachining, on the other hand, cannot offer such channel height control due to spatial variations in etching speed.

Buried Channel Technology

In buried channel technology, the idea is to create a deep access trench by direct anisotropic deep reactive ion etching of silicon.  The side walls are passivated by chemical vapour deposition, and a circular channel is then isotropically etched, with the bottom of the access trench centrally located. This technology is successful when very deep and narrow access features are used.

Bulk Micromachining

Without a doubt, bulk micromachining is the most commonly used method of micro-manufacturing. In this method, microfluidic channels are formed by removing excess material from a wafer and bonding or adhering it to another wafer to encapsulate the channels. Unlike surface micromachining, which uses a succession of thin film deposition and selective etching, bulk micromachining defines structures by selectively etching inside a substrate. Bulk micromachining can utilize either dry or wet etching techniques, but most commonly uses wet etch.

Citrogene: Glass Microfluidic Manufacturers

Citrogrene is the leading provider and manufacturer of glass microfluidic devices. We specialize in each of these methods, and are able to produce glass microfluidics with a fast turn-around rate at an affordable cost. To learn more about our glass microfluidic manufacturing services, contact us today.