Prof Steffi Krause
Dr. rer. nat., MRSC, FHEA
My research focuses on the development of chemical and biological sensors and electrochemical imaging. Also visit our group web page: Electrochemical Sensors Group
Light-Addressable Potentiometric Sensors (LAPS) and Scanning Photo-induced Impedance Microscopy (SPIM) are imaging techniques based on photocurrent measurements at electrolyte/insulator/silicon (EIS) field-effect structures. They are capable of measuring local changes in the surface potential (LAPS), which can be used to image ion concentrations, and of measuring the local impedance (SPIM). Recent highlights of our research are the achievement of submicron resolution of photocurrent measurements at silicon-on-sapphire substrates using a two-photon effect, the increase in the sensitivity of SPIM using organic, self-assembled monolayers as insulators, the use of SPIM for the interrogation of biosensor arrays, quantitative impedance imaging of polyelectrolyte microcapsules with high resolution and the measurement of cell surface charge and cell impedance. Recent development of LAPS with alternative non-insulated substrates allows detection of redox active molecules and hence a much broader range of analytes than with traditional EIS structures. LAPS and SPIM have great potential as tools for functional electrochemical imaging of the attachment area of cells, providing information such as ion concentration, extracellular potentials and cell impedance. The techniques are particularly attractive for analysing responses of cells with planar polarisation or cell types that separate one compartment from the other as the cell-surface attachment area is not accessible to conventional electrophysiological and electrochemical imaging.
Disposable biosensors for the detection of enzyme activities based on the enzymatic degradation of thin polymer films have been developed. Film degradation in the presence of an enzyme is monitored using impedance spectroscopy and a Quartz Crystal Microbalance (QCM). Inflammation and bacterial infection are frequently accompanied by increased levels of host and bacterial proteases. Current efforts are therefore directed at the development of polymers that are degraded specifically by different proteases. Our biosensor technology is of potential commercial interest. Biosensors for the detection of proteases have recently been developed with the primary goal of monitoring inflammatory conditions such periodontal disease and multiple sclerosis, however, other application such as protease detection for the detection of bacterial infection in food and wound management or monitoring of occupational exposure have also been envisaged.