Sampling: a critical problem in biosensing.

Biosensing is widely recognised to be of potentially major importance to medicine and related fields, but in spite of a large number of impressive and important advances, widespread practical application has lagged. We examine the thesis that 'sampling' is a process which involves all of the phenomena which are associated with the transport of analyte molecules to the active sensor site, and that problems associated with this process are now the limiting factor in further use of many existing biosensors. We conclude that an integrated process of sampling and sensing should be emphasised in developing new biosensing systems, and propose several new approaches.