Amperometric biosensors and potentiometric pH-microsensors integrated into AFM tips

Summary form only given. Scanning electrochemical microsensors offer unique advantages by combining laterally resolved information on electroactive surface processes with high sensitivity and selectivity. In order to position and scan nano- and microsensors at a constant distance across the sample surface, we developed combined scanning probes by integrating micro- and nanoelectrodes into AFM tips using microfabrication and focused ion beam (FIB) techniques. Further modification of the integrated electroactive area enables the implementation of microbiosensors by immobilizing a biological recognition element or by integrating a potentiometric pH sensor using a metal/metal oxide layer such as iridium/iridium oxide. The presented approach allows laterally resolved imaging of ATP concentrations above epithelial cells during AFM imaging and monitoring cellular ATP release. pH-changes in microenvironments can be laterally resolved with integrated AFM-pH nanosensors.