Functional surfaces in thin-layer and thick-layer technology

Sensors on flexible substrates

Functional surfaces in thin-layer and thick-layer technology

Colorimetric sensors for selective gas detection

Functional surfaces in thin-layer and thick-layer technology

Sensorarrays with gas-sensitive metal oxides

Development of materials and substrates using microsystems technology

For the manufacturing of miniaturized gas sensors and sensor systems as MEMS (Micro-Electro-Mechanical Systems) or MOEMS (Micro-Optoelectro-Mechanical Systems), as well as for nanoscaled metal and semiconductor structures, Fraunhofer IPM has a 400m² clean room of class 100/ISO 5 at its disposal. Here, tailor-made photolithographic processes and coating procedures are devised and manufactured. Functional surfaces of thicknesses ranging from a few nm to some µm are deposited on any substrate by means of sputtering, vacuum evaporation or an inkjet printer.

Deep-etched structures of a few µm using RIE and ICP etchers or wet chemical etching processes are used to integrate sensors onto a chip in bulk or hotplate technology and hence provide sensor technology for detecting parameters such as moisture, temperature and gas. Microstructured surfaces are the basis for IR emitters, e.g. for micro-optical applications. Functional surfaces on different substrates are thus turned into custom-tailored sensor systems with the help of specific cleanroom process technology.

Fraunhofer IPM is experienced in processing a wide spectrum of materials, ranging from metal oxides as SnO2, Cr2-xTixO3+z, WO3 or In2O3, to metals as Pt or Pd, conductive, transparent layers (TCOs) as ITO and anti-reflective layers as MgF2 or ZnSe to colorimetric materials.

This variety of techniques and materials is outstanding. Thus, Fraunhofer IPM develops customized and cost-efficient production techniques as well as gas-sensitive materials, and production procedures for of printed electronics. Our range of work includes the development of flexible transistor structures, but also the design of test structures or the characterization of polymer based semiconductors.

For materials characterization, Raman-, UV/VIS- and FTIR-spectroscopy as well as scanning electron microscopy (SEM) and atomic force microscopy (AFM) are applied.

A question of the appropriate measurement method

© Fraunhofer IPM

Semiconductor gas sensors (metal oxide sensors) are electrical conductivity sensors. The resistance of their active sensing layer changes due to contact with the gas to be detected.

The principle of the colorimetric sensor is based on a change in color of the gas sensitive layer when it comes into contact with the target gas. This color change correlates with the concentration of the gas.

Electronic tongues or sensors are based on thermal and electrical impedance spectroscopy. They allow measuring the chemical, physical and mechanical characteristics of liquids and solids.