Miniaturized thermophile sensors

The standard housing in such applications has for many years been the TO5 which measures 8.2 mm in diameter; yet the introduction of infrared ear thermometers prompted the market to look for smaller housing formats, and manufacturers worldwide now offer TO5 and TO18 housing, with an outer diameter of 4.7 mm.

However, there is a need for even smaller sensor designs with increased symmetry (without orientation nib) in order to make the relevant devices, such as the ear thermometer, forehead thermometer or also anesthetic devices, even smaller. The existing device sizes are almost impossible to use with babies and small children, for example, because the sensor head - as a result of the sensor’s dimensions - is too big to fit the baby’s inner ear. Here the market is looking for sensors with a smaller outer diameter and without the ‘orientation nib’ normally found at the bottom end of the housing. Further reductions in the size of the housing can, however, only be achieved if the size of the integral sensor chip is reduced and this miniaturized chip mounted in a corresponding housing using microsystems technology.

Under the direction of Prof. Friedemann Völklein, a simulation process has been developed, which optimizes the manufacturing process of extremely small thermopiles. This creates the conditions for fine-tuning the technology used in thermopile manufacture, leading to the joint development of the world’s smallest thermopile.

The ability to manufacture smaller sensors also leads to changes in device construction. The design of new devices with substantially smaller measuring heads, such as are used in baby ear thermometers, is no longer determined by the sensor’s size, but rather by ergometric design considerations. Over the next two to five years, the market share of IR thermometers is set to increase and further reduce costs in the process.