Utilizing interfacial impedance- and heat-transfer phenomena in advanced monitoring- and switching devices

Electrochemical impedance spectroscopy (EIS) is an established technique for probing the conductive and dielectric properties of matter in wide frequency ranges. Applications are numerous and cover the determination of salinity of sea water equally well as the detection of neurotransmitters and proteins in food- and blood samples. The applicants have found a ‘thermal counterpart’ to impedance spectroscopy in 2012 in which the electrical current is replaced by a thermal current: This ‘heat-transfer method HTM’ has proven useful in various bio-analytical tasks and advantages over impedance spectroscopy are seen in the fact that HTM can operate easily with electrically insulating sensor-chip materials and non-conductive liquids. Within this proposal, we will aim at integrating EIS and HTM into a combined methodology to be employed in two exemplary applications: i) The monitoring of bacterial film formation at solid surfaces and ii) the monitoring of degradation processes of biocompatible polymers. Moreover, we will utilize the EIS & HTM combination in order to study switching effects of thermal- and electrical currents through iii) pHresponsive polymer layers and iv) molecular brushes of DNA. The switching effects will be triggered by conformational changes of the DNA- or polymer layer upon exposure to electric fields or a changing pH. Provided that the concept works it would be novel technique for controlling electrical and thermal currents based on tunable interfaces.