The State Ministry for Economic Affairs, Climate Protection, Energy and Regional Planning of Rhineland-Palatinate awards an annual innovation prize in cooperation with the committee of the Chamber of Industry and Trade of the federal state, to particularly innovative individuals or bodies from Rhineland-Palatinate in recognition of their achievements and their contribution to innovation in the economy of the federal state. The winner in the manufacturing category 2013 (and already repeatedly in previous years) was WICKERT Maschinenbau GmbH.
With Labs on a Chip, miniaturization has long since found an entrance to analysis in chemistry and biotechnology. The expression “Lab On a Chip” (LOC) characterizes a microfluid system which accommodates the function of a macroscopic laboratory on a chip of only a few mm2 to a few cm2.
This technology allows the complete and automatic analysis of the most minute quantities of a liquid down to zu 1 pico Liter (= 0.000000000001 Liter) on a single chip. The transport of the samples between the various reaction and analysis chambers takes place with the help of capillary forces.
Replacing photolithography, micro-embossing and high end thermo-diffusion bonding. The basis for the production of LOCs used to be photolithography. Disadvantages of this process are especially its limits in accuracy of analysis, which result from limitations in mechanical precision. Add to this the relatively high production costs resulting in high costs per LOC. Exposing and eroding – as in the case of electronic chips – is relatively expensive.
One starting point in the improvement of the cost efficiency of LOC production was the substitution of high-performance plastics for the silicon baseplate of the chip. The plastic baseplate had to be micro-embossed in a first step for this, in order to accommodate the required micro-channel systems. But the decisive achievement consisted in the development of a process to seal the baseplate, filled with reaction fluids, to the cover plate with the highest precision. The step was achieved by way of thermodiffusion bonding. WICKERT was tasked with developing a device which first produces the required structures with hot pressing, and finally fixes the cover on the baseplate with its chemical filling.
Hot embossing plant is available on the market. Consequently the main challenge for WICKERT was to build a machine for themodiffusion bonding: A micro-embossing machine is in essence a suitable machine for thermodiffusion bonding. Thermodiffusion bonding – much better than “state of the art” But the thermodiffusion bonding for the required process had still further requirements which extended beyond the state of the art at the time, in particular
- Taper compensation in the area of the press plates < 5 μm over the whole area of ø 200 mm.
- Vacuum chamber suitable for vacuum to 1 mbar and also for protective gas atmosphere within the chamber with up to +2.5 bar pressure (normal vacuum chambers allow only vacuum but no positive pressure).
- Heating and cooling rates of 40 kelvin/min within a vacuum chamber. (State of the art was about 20 kelvin/min.).
The required new and further developments beyond the state of the art were successfully achieved.
a) Tempering with heating and cooling rates up to 40 kelvin/min. Important steps in this development consisted of special heating/cooling plates with a graphite insert for very fast heat transfer combined with pressure stability up to 30,000 N and the required mechanical precision (flatness within 1 μm).
Compensation of the thermal expansion of heating/cooling plate and also in piping system within the vacuum chamber.
b) Novel taper compensation.
c) Vacuum chamber system with novel sealing system, suitable for 1 mbar vacuum and + 2.5 bar pressure. The greatest challenge here was to get the sealing system to slide as smoothly as possible along the opposite surface to avoid influencing or falsifying the joining force.
Thanks to WICKERT’s development of this system, the production costs of Lab On a Chip were reduced in comparison with previous production methods, delivering impressive savings. Typical advantages of LOCs are:
- Minimal use of liquids and the associated lower costs and reduced requirements for reagents for samples, as well as less waste.
- Shorter analysis and reaction times and lower heat capacity resulting in better process control.
- Compact solution, featuring high functionality in connection with the most compact dimensions and volume.
- Safer platform for investigations thanks to lower fluid volumes and less stored energy.