Photoresist microelectrodes

Preparation of Microelectrode Arrays. The microelectrode arrays used in the work were arrays of microelectrodes each 80 pm long, 2.3pm wide and 0.1 pm thick and 3paced 1.7 pm apart. Fabrication and encapsulation of the microelectrode arrays has been described previously.<14.15.21-22) Prior to use, arrays of microelectrodes were cleaned by an rf 02 plasma etch to remove residual photoresist, followed by cycling the potential of each electrode between -1.5 V... 

Figure 11.6 Fabrication procedure of an IDA microelectrode. An oxidized silicon wafer (A) is coated with platinum (B). Carbon film is pyrolyzed on it (C). The substrate is coated with photoresist, which is exposed and developed (D) unnecessary portions are then removed by reactive ion etching (E). After removing the photoresist, an Si3N4 layer is deposited on the substrate (G). The substrate is coated with photoresist, which is exposed and developed (H) then the desired shape of the carbon electrode is exposed by reactive-ion etching (I). [Adapted from Ref. 36.]...

Figure 15.6 Phase shift of the EHD impedance corresponding to the ferricyanide reduction on a platinum electrode (area 0.38 cm ) coated with a photoresist on which an array of circular sites of diameter dact was patterned, dact = 649 fim, Ci — 96 rpm ( ) and 375 rpm (A). Theoretical curve for a single microelectrode (dashed line), or for the active disk electrode (solid line). (Taken from Deslouis and Tribollet. )...

Figure 1.14 Process steps for the preparation and electrochemical measurement of photoresist microelectrodes. All steps are carried out under microscopic control with micromanipulators to handle the mask and the microelectrodes GE, counter electrode RE, reference electrode ME = working electrode. (Method introduced by Kudelkaand Schultze 1993 [6].).

General Aspects It is beyond the scope of this treatment to discuss the current and potential distribution for photoresist microelectrodes in detail. Therefore, only a few comments will be made on the influence of the geometry and the resist barrier on electrochemical measurements. Photoresist microelectrodes can be treated as a recessed microdisk electrode. The diffusion field and the current distribution are... 

Photoresist Microelectrodes The local cyclic voltammograms on photo-resist-microelectrode prepared on grains 1 and 2 are shown in Figure 1.33a. Clearly, the shape of the curves is different for each case. On grain 2, the measured anodic... 

Three-Dimensional Electrodes, Fig. 2 Array of carbon microelectrodes prodnced by pyrolyzing photoresist [14], (Reproduced with permission from each of the publishers)... 

The development of the resin to form microelectrode arrays is mostly based on the lift-off process (164). A solvent dissolves the remaining soluble positive photoresist underneath the metal, starting at the edge or lip of the unexposed photoresist and lift off the metal in the process (Figure 10.13). When the photoresist is removed, all metal on top of the photoresist strip strips off automatically while metal on the top of the photoresist lines stays. 

A more common approach that also allows one to control a critical parameter, the separation between neighbouring microelectrodes, is through the use of photolithography which is based upon photoresists (light sensitive chemicals) and exposure tools such as UV sources [1, 16]. The fabrication process of gold disc microelectrode arrays is highlighted within Figure 6.2 [17]. 

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...

Photolithography is the most diffused technique for the fabrication of regular arrays of microelectrodes. Photolithography is a microfabrication technique which is based on the selective removal of parts of thin films (photoresist) exposed to UV light. This procedure allows one to obtain regular arrays of micro electrodes with high spatial resolution, nonetheless this technique requires special and expensive equipments besides, the photolithographic process requires access to a clean room. 

Photolithographic definition of the openings of microelectrodes and external contact pads. The photoresist is used here for electrical isolation of the metal tracks. 

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