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 for the detection of charged molecules such as DNA, quantitative impedance imaging of polyelectrolyte microcapsules with high resolution and the measurement of cell surface charge and cell impedance.
Recent development of photoelectrochemical imaging with semiconducting metal oxide substrates such as indium tin oxide and hematite allows detection of redox active molecules and hence a much broader range of analytes than with traditional EIS structures. Combined with a recently developed fast imaging setup, the technique has shown great potential for continuous functional electrochemical imaging of the attachment area of cells, providing information such as ion concentration, extracellular potentials and cell membrane permeability. Photoelectrochemical imaging is 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.