Integrated Microfluidic µDialysis Probe

Microdialysis is a commonly used technique in studies of drug metabolism in neuropharmacology. It is a minimally-invasive sampling technique that allows for continuous measurement of free, unbound analyte concentrations in the extracellular fluid of virtually any tissue. Aim of the project is to integrate a microdialysis probe into existing microfluidic platform using common micro- and nanofabrication techniques.

Miniaturisation of the probing device coupled with advantages provided by microfluidic technology allows to benefit from reduced analyte usage, improved concentration ranges of analyte in sample, sensitivity, time resolution and limit of detection, ability to do a localized perfusion and sampling. Common and experimental fabrication techniques employing photocurable resists (SU-8), basic photolithography and bonding processes are used widely (Fig. 1). Among these are self-generated polymer membranes made by means of controlling solvent concentration of the resist and UV radiation dose. Initial studies of the device are carried out in PDMS (Fig. 3) employing electrophoretic gels as a diffusion media and soft lithography.

Figure 1 Diffusion area design and microfluidic circuitry in the material SU-8

Figure 2 Diffusion zone of a PDMS chip