Polyimide-based microelectrode

Fig. 9 Polyimide-based microelectrode with integrated microfluidic channel. The U-shaped channel has a fluid delivery outlet at the tip of the probe [63]...

Fig. 7 Fabrication process for polyimide-based thin-film microelectrodes. The silicon substrate acts as a mechanical support during fabrication, and in the last process step the probes are removed from the wafer [53]...

Fig. 11 Thin-film parylene-based microelectrode with embedded microfluidic channel. The pary-lene is structured in a reactive-ion etch. The photoresist serves as a sacrificial material, and it defines the channel shape. As with the polyimide fabrication process, the silicon substrate serves as a mechanical support during fabrication, and the parylene probe is removed in the last step. In this injection test, ink is passed through the microfluidic channel [67] - Reproduced by permission of The Royal Society of Chemistry...

A recent report of an in vivo flexible strip microelectrode sensor array for glutamate and lactate monitoring in tissue represents an advance [44], The polyimide substrate was patterned with platinum microelectrodes in addition to epoxy and dry film insulations to produce amperometric, enzyme-based sensors. An on-chip reference electrode and a perm-selective layer, with hydrogel membranes or direct cross-hnking for enzyme immobihzation, provided stable devices with good performance and allowed a demonstration of in vivo application to glutamate monitoring in rat brain. 

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