Each material has different characteristics and we have to choose the technology for the micro-structuring accordingly. For metal, the relevant technologies are precision mechanincal maching, laser machining, and electro discharge machining. For silicon, we use wet chemical etching and dry etching (DRIE). Wet chemical etching is also a suitable technology for structuring glass, but in addition to that, direct laser structuring, powder or sandblasting as well as photostructuring can be chosen according to the requirements. Elastomers can only be processed via casting.
Materials and Underlying Technologies
The most flexible material is the thermoplastic polymer. Thermoplastic polymers can be processed via injection molding, thermoforming, hot embossing, laser machining, and precision mechanical machining. Here injection molding as a replicative technology allows for the most cost-efficient fabrication of micro-structured devices. We mainly use thermoforming for generating blister packs.
The fabrication of a lab-on-a-chip system requires more than just the micro-structured part. Usually, you need at least a cover lid placed on the micro-structures, requiring special assembly technologies. For glass and silicon, established processes are at hand, easily exceeding 100°C temperature, even for “cold” processes. The elastomer silicone can be easily mounted onto itself or glass and silicon, but the joint can be released. For thermoplastic polymers, we developed several technologies, which allow us to join parts without harming microstructures and to work without elevated temperatures, preserving embedded reagents or deposited biomolecules.