The difficulty in overmolding a temperature sensor with plastic, for example, has so far been that plastic has low thermal conductivity and is therefore not ideal for temperature measurement. Another complicating factor is the extreme ambient conditions during injection molding: the liquid plastic reaches temperatures of up to 360 °C, the closing pressure of the machine is up to 100 t and the pressure in the mold is up to 1200 bar. Despite these unfavorable conditions, Jumo has established a functioning production process:

The problem of thermal conductivity is solved in the "Plastosens" products using special plastics with special additives. According to Juno, there is hardly any difference in the end result compared to metal sensors. A positive side effect of these special mixtures is that a plastic can be developed for each customer that is precisely tailored to the respective application. Other additives used in the thermoplastics include colorants, light and flame retardants as well as reinforcing fibers. Jumo subsidiary PGT Prozesstechnik provides the know-how in the field of injection molding technology.

Jumo describes the complete freedom of form as the greatest advantage of plastic sensors. The products adapt to the respective installation situation - for example, a temperature sensor can be completely integrated into a plastic pipe. Or it is round, spiral-shaped and has an angle.

Further advantages of plastic are its low weight, reproducibility and insulation resistance. This makes it easier to use the sensors in environments with very high currents and voltages (e.g. electric motors or transformers).

Depending on the plastic mixture, the "Plastosens" temperature sensors can be used in a temperature range from -50 to +200 °C. However, the manufacturing process requires a rethink compared to conventional temperature sensors: the sensors are developed in close cooperation with the customer. The process starts with a feasibility study and a design proposal and continues with the design and simulation of the temperature sensors and the construction of the injection molds. After a sampling phase, the tests begin, culminating in a functional prototype and series production. With the help of modern simulation software, the response behavior and heat dissipation capacity of the planned temperature sensor can be simulated early on in the development process.

Currently under development are a sensor with an insulation strength of 5 kV for use in transformers, a vibration-resistant insertion sensor for the medium oil - initial tests have shown that the sensor can withstand forces of up to 20 g without any problems - as well as a water and steam-tight sensor for sterilization applications.

Whether other measured variables - such as pressure or liquid analysis - can also be realized with the new technology is currently being tested.