speedwave microwave digestion: the success story of a patent

Berghof Products + Instruments GmbH revolutionized the microwave digestion market by inventing and patenting the contactless in-situ temperature measurement of samples in digestion vessel.

The advantages of rapid heating rates of microwave instruments had been decisive for the fact that since the end of the 80s of the last century, microwave devices were not only used in the kitchen, but were also increasingly utilized in chemical laboratories. However, the use of microwave instruments in laboratories was in the beginning sometimes challenging. The pressure vessels and their contents were heated in an uncontrolled manner and without monitoring the reaction parameters. It was therefore not possible to observe and control the microwave digestion process, thus in the case of spontaneously induced exothermic reactions no proper action could be taken.

At that time, several manufacturers of microwave digestion systems started working on overcoming this challenge. The ultimate breakthrough was introduced by Dr. Rainer Krämer an experimental physicist with experience in infrared spectroscopy, working with Berghof Products + Instruments GmbH (at that time operated under Berghof Labor- und
Automatisierungstechnik GmbH). He discovered that with the PTFE material used for the manufacturing of the digestion vessels an infrared beam could be used for the direct measurement of the sample temperature inside the vessel. Based on this knowledge, he developed a detection system that was patented and is still used in the Berghof microwave digestion systems today.

On April 14, 1994, a patent application for the measuring system was filed, named as "device for in-situ temperature measurement of a sample in a pressure vessel". The patent DE 4412887C2 was granted on October 29, 1998. This technology can still be found under the name speedwave® DIRC (Direct Infrared Control) in the Berghof microwave digestion systems speedwave XPERT and speedwave ENTRY.

In addition, Dr. Rainer Krämer developed two further sensor technologies for measuring the internal pressure inside the vessels and for measuring the outer surface temperature of the vessel. Speedwave® OPC (Optical Pressure Control), the technology for the measurement of the internal vessel pressure, was also patented (DE 19710499A1). The revolutionary aspect about speedwave® OPC is that for the pressure measurement inside every individual vessel is possible without the requirement for an additional reference vessel.

Applying Speedwave® OTC (Optical Temperature Cut-Off), the functionality for measuring the vessel surface temperature, allows the setting and control of an upper temperature limit of the outer surface of the vessel. This increases user safety and the operating life of the vessels.

The patented optical sensor technologies from Berghof not only allow contactless pressure and temperature monitoring in real time, but also individual monitoring of all vessels and their reaction parameters. Since the optical sensors never come into touch with the samples, contamination is excluded. In addition, handling is extremely user-friendly, since no reference vessel needs to be cabled or equipped with temperature probes.