This paper concerns the study and use of biological cells in which there is a need for sensors and assemblies for the
measurement of a diverse range of physical and chemical variables. In this field cell culture is used for basic research
and for applications such as protein and drug synthesis, and in cell, tissue and organ engineering. Metabolic processes
are fundamental to cell behaviour and must therefore be monitored reliably. Basic metabolic studies measure the
transport of oxygen, glucose, carbon dioxide, lactic acid to, from, or within cells, whilst more advanced research requires
examination of energy storage and utilisation. Assemblies are designed to incorporate bioreactor functions for cell
culture together with appropriate sensing devices. Oxygen consumption by populations of cells is achieved in a flowthrough
assembly that incorporates O2 micro-sensors based on either amperometry or fluorescence. Measurements in
single cell are possible with intra-cellular fluorophores acting as biosensors together with optical stimulation and
detection. Near infra-red spectroscopy (NIRS) is used for analysis within culture fluid, for example for estimation of
glucose levels, as well as within cell populations, for example to study the respiratory enzymes.£
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