German Engineer Heinz Ploechinger was awarded this year’s R&D 100 Award for his dual-axis thermodynamic inclination and acceleration sensor (TDNS). The Chicago Tribune has called the R&D 100 Awards the "Oscars of Invention", others have referred to the awards as "the Noble Prizes of applied sciences". Thus the sensor is counted among the best 100 technological inventions and developments of the year 2001.

A completely new sensor technology

Conventional acceleration and inclination sensors are based on mechanic devices. The problem: those devices are quite delicately. Accurate measurements, though, are very important for safety, for example in automotive industry. Here a sensor has to decide in a split second whether and when to release the airbag to safe the driver’s life. This is where the new sensor comes in. In addition to conventional airbag sensors the TDNS is constantly measuring the car’s current inclination and acceleration. This data is passed on to the central electronic system of the car. In case of an accident the electronic system in correlation with the conventional airbag sensor is able to release the airbag at the appropriate moment to keep the driver safe. Thus the TDNS adds to car safety and helps to prevent accidents.

Mr. Ploechinger constructed a prototype of his new sensor already in 1993. The sensor is aligned directly to the center of the earth, just as a perpendicular is. Due to this principle, the sensor is able to provide accurate measurements along both the x- and the y-axis and even works headfirst. This is a fundamentally new principle of measuring movements.

Principle of operation

But how does the new sensor work? A heating element integrated in a gas filled case produces a convection current along the gravity field. Highly sensitive temperature dependent resistive elements detect the temperature of the surrounding gas flow. Any movement of the sensor (inclination or acceleration) causes an imbalance between the resistive elements which is detected by the electronic circuit. The sensor stands out due to his small dimensions and his extreme robustness.

Areas of application

It seems as if the sensor was developed at the right time, as the possible areas of application increase continually. A current example is the "human transporter", which was recently introduced in press articles as the future means of transport for short distances.

Especially in the automotive industry the sensor can be applied extremely well. It can be used for roll over detection, automotive anti theft systems and suspension control, thus helping to reduce the number of car accidents. But the sensor also proves useful for crane and construction machines and low g measurement.

The dual-axis thermodynamic inclination and acceleration sensor has already won two awards in Germany prior to the R&D 100 Award 2001.


More Ploechinger patents

The thermodynamic inclination and acceleration sensor, however, is not the only invention made by Mr Ploechinger. He holds several other patent rights in the area of sensor technology (most of those licenses are still available. For further information see

For example: the capacitive level sensor. This sensor measures the level of a fluid within a container (for example oil, water, gas), ignoring the container’s current inclination. It was constructed to replace the old float–lever–system, which is cheap in production but quite inaccurate and temperamental.

Or the seat occupation sensor , that scans the co-driver’s seat in a car. If the seat is empty, the sensor signals to the airbag that it does not need to be activated in case of a collision. This saves on costs, as exchanging a used airbag is rather expensive. If the seat is occupied by a child, the sensor passes on appropriate data to the airbag sensor, which adjusts the position of the airbag according to the child’s size. Thus accidents are avoided in which children are suffocated or killed by activated airbags.

Insurances may find the head rest inclination sensors useful. Here a sensor is measuring the body of the seat’s occupant and adjusts the head rest accordingly. In case of an accident, the risk of whiplash is thus decreased. For this sensor a prototype has already been constructed.

Useful for travelling long distance by airplane is the locally limited climate zone. In airplane cabs humidity values can drop down to 1% relative humidity only, often causing problems for the passengers by drying out the mucous membrane, skin and eyes (especially unpleasant for people wearing contact lenses). The climatic mask is able to buffer breathed out humidity, thus supplying healthy air with humidity values of 50-70 %. The mask may also serve as a carrier for inhalation and odoriferous substances.


On the inventor

Heinz Ploechinger was born in Bavaria, Germany. He studied electrical engineering in Munich. Already at his first employment he was working in the area of measurement procedures at a company that produces electronic parts. After that he worked in development and technical consulting of a measurement and control engineering company, of which he was also leading its Munich branch. In 1970 Mr Ploechinger founded his own company, Thyracont Ltd. , which has developed into one of the leading companies for vacuum measurement procedures since then. For several years now Mr Ploechinger has also been conducting the patent rights company Ploechinger Patents in Austria, where he has marketed his own patents so far.

R&D Magazine, October 2002