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Karl Stock helps turn ideas into products

Karl Stock takes abstract ideas and turns them into useable technological possibilities. The 44-year-old works in what could best be described as the one-man engineering office at the Ulm-based Institute of Laser Technologies in Medicine and Metrology (ILM). In contrast to university institutes, Stock’s work does not simply finish with a “paper” published in a journal. Stock strives to go further and his real work starts where others often stop, and this extra work may well lead to a functional model or prototype.

Karl Stock - Head of Development at the ILM © Pytlik

Stock has a PhD in human biology and an engineering degree from the Aalen University of Applied Sciences. Stock says that his work lacks major focal points, but this is something of a modest understatement. He is possibly referring to the time taken to carry out his duties relating to his "pivotal" position as vice institute director, a post he has held since 2008. He is the person where all lines, i. e. projects that are close to application and that are in different states of development, merge. All the projects at the Institute, ranging from microscopy, metrology, medical laser application and optical design, are carried out on behalf of industry.

The ILM's "Application Research" and "Device and Component Development" departments focus on development and bring together all the various areas of expertise in engineering at the ILM. The ILM's mechanics and electronics workshops are also part of these two departments.

The ILM's "Application Research" division focuses on the requirements of therapeutic and diagnostic processes, often using physical experimental series. The researchers measure and simulate tissue effects, develop feedback systems or therapy control methods. This leads to drafts, constructs and devices - laser devices, components and applicators. Karl Stock ensures that the optical design is implemented and the optical fibres modified. With his joint roles as head of development and lecturer at the University of Ulm where he teaches a medical technology master's degree course, Stock increasingly finds he needs to delegate different aspects of his work.

An indirect route towards his goal – outstanding PhD thesis

Chromatically encoded distance measuring, a special 3D measurement technology. Karl Stock has great faith in this technology, in particular with regard to strongly scattering or semi-transparent objects. © ILM

Stock was offered a job at the ILM through pure chance, meaning that he was thus able to remain close to his hometown (Ellwangen). Normally, fine mechanics (now called mechatronics) graduates from the Aalen University of Applied Sciences tend to look for jobs in industry. This was not the case for Stock who did his diploma thesis at the Ulm-based ILM under the supervision of Raimund Hibst. Stock was fascinated by medical laser technology and he realised that he was more interested in research and development than in becoming an engineer. Nevertheless, he started at the ILM in an engineering post where he worked on industrial and publicly funded research projects, as well as supporting the development of laser-assisted therapies in dentistry, dermatology, middle ear surgery and ophthalmology.

After a while, the then 30-year-old had to decide what he wanted to do next. Did he want to leave or did he want to accept a permanent position at the ILM? He followed the advice of his supervisor from the Aalen University of Applied Sciences, Prof. Herbert Schneckenburger: after passing an entrance exam at the Medical Faculty at Ulm University, he went on to do a doctorate for which he received an outstanding evaluation.

Stock's doctoral thesis focused on the development of a microscopic set-up for the depth-resolved fluorescence measurement under total reflection conditions. This method (which is still used at the Aalen University of Applied Sciences) makes it possible to examine cell substrate contacts in nanometre resolution and the transport of substances through the cell membrane. Stock further developed this application and designed a special illumination condenser for the microscope. However, in the end luck was not on his side and he was unable to commercialise his invention.

Following his outstanding doctoral thesis, Karl Stock had got to where he wanted to get. He left his engineering post and accepted a post as scientist at the ILM in 2001. Seven years later, together with the institute's director, Prof. Raimund Hibst, and Alwin Kienle, Stock is involved in determining the ILM's future.

A broad field: from the basics to product development

Stock’s activities go far beyond the value creation chain of university institutes; they include basic and applied research as well as product development, in particular optical design. Once the requirements for a certain optical device have been defined, system specifications will be determined and a device developed and tested in clinical studies. This requires someone like Karl Stock, who deals with all issues on both sides of the fence ranging from the in-house results to the ideas of the user, production, product management, price and marketing. Stock often also has to coordinate management activities and patent searches.

“We try to reconcile this broad range of different requirements in order to develop a suitable device or product,” said Karl Stock describing the multi-tier process. He believes that this is the strength of his employer: a broad range of services offered by a single institute where there are no conflicts of interest; ILM manages projects for some of its clients, coordinates the work tasks, sets deadlines, arranges surgery dates with clinicians or in the ILM’s own Laser Therapy Centre. Stock also believes that the ILM has another particular strength: the institute is able to provide inventive solutions and suggestions to resolve unusual issues.

Getting to the roots of problems

Laser handpiece for use in oral surgery. © ILM

A project that has been running since 2007 is a good example of what development means for the ILM. The ILM, with its excellent reputation and excellent contacts in the field of dentistry, suggested an improved diode laser to a company, whose name remains undisclosed, for use in dental applications. A normal diode laser uses the same optical fibres for different applications. The Ulm researchers therefore suggested the use of a diode laser consisting of an optical fibre with a handpiece with exchangeable tips. These tips can either be disposed of or sterilised; they can be optimised for certain applications, in this particular case they are being used to cut soft tissue (oral surgery) and to disinfect the root canal (endodontic treatment).

Using a specific fibre (centre), cuts can be made more effectively in the soft tissue. © ILM

Initially, the course of the ablation process was determined. This is basic science. Subsequently, the scientists focused on developing a solution for the oral and surgical application of the diode laser: it appeared to be obvious that the length of the initialisation phase needed to be reduced, the light focused and its intensity increased in order to produce the heat required more quickly at the site of application and achieve carbonisation.

In the subsequent design of the device optics, the ILM can benefit enormously from its huge expertise in the light scattering of optical fibres. Initially, the researchers tested a broad range of different geometries to focus the light. The simulations suggested that a spherical shape was the most effective, and the mechanics workshop went on to construct a preliminary handpiece. This handpiece was subsequently used to cut supermarket-purchased meat. Although this seemed to work well, the ILM's application researchers nevertheless found that the spherical shape was not as good as they had initially thought. They found that the laser beam can be best focused in the area where the beam leaves the device, and additional experiments finally led to the development of a conical tip.

A broad range of competences

Besides engineers, histologists and the precision mechanic who used a tiny sapphire to give the handpiece the desired conical shape, dental expertise was also taken on board in this phase of development. In collaboration with the client, the ILM decided on the supplier of the materials before the ILM workshop manufactured an ergonomic and geometrically optimised handpiece, which was finally used to prepare histological sections from more specific material.

Academic services are also part of Stock’s activities

Tissue section with sapphire. © ILM

Once there was evidence that cuts could be made with twice the speed as the reference system (milestone), the present case left the ILM's responsibility. The final design, which of course the ILM would also be able to provide, was done by the contracting company who presented the prototype at a recent exhibition. The ILM presented a scientific poster on the development of the handpiece. The ILM also presents basic scientific findings at scientific congresses, as they did for the second subproject. ILM biologists discovered that bacteria present in the root canal are not killed by the laser light but by the heat it emits. These findings were obtained from complex experiments involving E. coli bacteria.

It is much easier to carry out such basic science-oriented scientific work as part of publicly funded cooperative projects. Such projects give the ILM better planning options and generate fewer risks than milestone-dependent industry projects. Karl Stock is therefore hoping to acquire public funding for additional development projects.

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