We report on our newest studies of electrically conductive interpenetrating polymer networks (IPNs) for application in temperature micro sensors. We manufactured polymeric structures on glass with a micro pattern generator by exposing a combination of Novolak and Terthiophene doped with copper(II) perchlorate with a UV laser. We assessed the effects of prolonged temperature loads on the structures’ impedances in a range of 30 to 130 °C. Such polymers and our approach may be of interest for the fabrication of different micro sensors, particularly when only a limited number of highly specialized sensors is required, e.g. for fire safety infrastructure.

ZusammenfassungIn diesem Beitrag präsentieren wir die Fertigung polymerer, diskret gestufter spiraler optischer Phasenplatten (SPPs) für die Erzeugung von Ringmoden in Laserstrahlen. Wir beschreiben das von uns verwendete Modell um die Wirkung von SPPs im Fernfeld abhängig von ihrer Geometrie zu simulieren und diese zu dimensionieren. Weiter berichten wir von der Fertigung zunächst 3- und 4-stufiger SPPs aus dem Negativlack AZ nLOF 2070 auf Kalk-Natron-Glas durch Spin Coating und Polymerisation mittels direkter Laserlithografie. Wir zeigen die Wirkung der Bauteile auf das Strahlprofil eines Helium-Neon-Lasers im Fernfeld und validieren damit auch das verwendete Modell.

Polymers hold great potential for the use in microsensors and organic electronics. They are highly adaptable, easy to process and can contribute new or improved capabilities compared to semiconductors. Direct UV laser lithography also gains increasing attention. Because it avoids expensive photomasks, it is especially attractive where small numbers of specialized microcomponents are needed, like in prototyping. Lithography necessitates materials, which can be shaped by UV radiation. For many microsensor applications, there is the additional requirement of electric conductivity, preferably in the same material. We approached this demand by combining a novolak and terthiophene doped with copper(II) perchlorate to form an interpenetrating polymer network, which possesses properties of both of its constituents. From this, we manufactured test structures with the UV laser of a micro pattern generator. In previous conference contributions, we showed a first proof of principle. In this publication, we present results of new experiments that demonstrate the characteristics in more detail. We improved our electrical setup to conduct four-terminal measuring. We used it to first verify previous results and investigated the material’s response to alternating currents up to 10 kHz. We then compared the electrical resistivity of differently sized structures for temperatures between 20 and 90 °C and examined long-term stability of their resistance by subjecting samples to temperatures of up to 60 °C for several hours. Additionally, we tested the influence of UV radiation on the resistance. Our samples exhibited good lithographic qualities. Resistivities were around 2 Ω mm and temperature sensitivity up to −407 Ω K−1. UV radiation induced a partially reversible increase of the electric resistance. The long-term stability of the material was temperature-dependent.