Micro-gearwheel, diameter: 0.26 mm, nickel, scaled against the size of an ant, photograph: Gerhard Schüler, 1986, black-and-white negative, 3.6 × 2.4 cm. KIT Archives 28028/19225.
The ant with the micro-gearwheel, affectionately named Henry, has long served as the iconic motif of the Institute of Microstructure Technology (IMT) at KIT. Gerhard Schüler, who worked at the institute, created this electron microscope image to visually represent the minute scale of the gearwheel by comparing it to an ant. The institute had developed the capability to manufacture such high-precision micro-components while working on an uranium enrichment method that required the mass production of millimeter-sized nozzles. At that time, it was known as the Institute of Nuclear Process Engineering and had to develop its own manufacturing method to meet the process’s demands. After the discontinuation of research on uranium enrichment, the institute shifted its focus entirely to microfabrication processes, partly because there was potential to transfer its innovations to industry. In 1989, it was renamed the Institute of Microstructure Technology. The micro-manufacturing process developed at the institute has since been applied in various fields, such as the production of components for microsurgical and dental devices and gears for high-quality watches. Microworks, a company founded as a spin-off of IMT, acquired a manufacturing license for this technology. Since then, micro-manufacturing techniques have continued to evolve. Today, the institute’s primary focus is on 3-D nanoprinting. kn
The trend toward miniaturization has been ongoing since the early days of semiconductor technology. By the late 1980s, many believed that the shorter wavelengths of X-ray light were vital in the manufacture of tiny structures. This hypothesis, coupled with the need to manufacture separation nozzles with small radii of curvature, led to the development of the LIGA process at the Institute of Nuclear Process Engineering. LIGA is an acronym for “Lithografie, Galvanik, und Abformung” and involves using X-rays from a synchrotron for lithography, electroplating to fill the resulting polymer structures, and mold casting to replicate these structures, in order to be able to produce inexpensive products with intricately crafted tools. The coupling of lithography and electroplating is a very common production method, such as for printed circuit boards. However, the LIGA process’s combination of X-ray lithography, electroplating, and molding is a specialty of Microworks GmbH, a spinoff from the Institute of Microstructure Technology. Components produced using this technique often feature tall, narrow structures, typically fabricated 10 to 20 times taller than their width — sometimes even up to 50 or 100 times taller — with line widths as small as 0.5 µm. Sloped structures on a substrate are also typical for this process. The Microworks company was founded in 2007 following a successful sponsored project that developed precision parts for Swiss watches — a market that continues to require the X-ray-based LIGA process. Another application of this technology is the gearwheel attached to Henry’s feeler. The smallest playfree gears currently available on the market are made of such components. Proximity to KIT and ongoing collaboration with its institutes are essential to ongoing research at Microworks and thus the transfer of LIGA technology to commercial applications. The Zeiss Innovation Hub@KIT, now located not far away, grants its employees quick access by e-scooter to the synchrotron radiation source on KIT’s North Campus, to take X-ray lithographic exposures. Access to facilities at the Institute of Microstructure Technology on a pay-per-use basis is also important, for instance, to quickly produce the masks needed for the LIGA process. Joachim Schulz (†)
The micro-gearwheel symbolically stands for the conquest of biological dimensions by engineering. The first step toward the dream of a submarine navigating the human circulatory system. Mathias Heckele, KIT, Institute of Microstructure Technology