These solutions must be carefully prepared in order to ensure good bonding strength is developed. These treatments can be made more effective by increasing the time and temperature of the application. However, too long of time can lead to excess reaction products that form and can hinder the bonding performance between the adhesive and adherend. As with other surface preparation methods, a good test to assure a good chemical treatment is to put a drop of water on the surface of the adherend. If the drop flattens or spreads out, it means the surface of the adherend has good wettability and should allow for good bonding. A final consideration when using chemical treatments is that of safety. The chemicals used in the treatments can be hazardous to human health and before using any, the material safety data sheet for the particular chemical should be referenced. Ultraviolet radiation treatment Ultraviolet (UV) radiation plays a role in numerous surface treatments, including some of the fore mentioned treatments, although it may not be the dominating factor. An example of a UV treatment where UV radiation is the primary factor that effects the surface preparation is with the use of excimer lasers. Excimer lasers are extremely high energy and use to create pulses of radiation. When the laser makes contact with the surface of the adherend, it removes a layer of material, therefore cleaning the surface. In addition, if the UV radiation laser treatment is performed in the presence of air, the surface of the adherend can be oxidized, thus improving the surface energy. Finally, the radiation pulses can be used to create specific surface patterns that will increase surface area and improve bonding. SU-8 Overview SU-8 is a 3 component UV-sensitive negative photoresist based on epoxy resin, gamma butyrolactone and triaryl sulfonium salt. The SU-8 polymerizes at approximately 100 °C and is temperature-stable up to 150 °C. This polymer adhesive is CMOS and bio-compatible and has excellent electrical, mechanical and fluidic properties. It also has a high cross-linking density, high chemical resistance and high thermal stability. The viscosity depends on the mixture with the solvent for different layer thicknesses (1.5 to 500 µm). Using multilayer coating a layer thickness up to 1 mm is reachable. The lithographic structuring is based on a photoinitiator triaylium-sulfonium that releases lewis acid during UV radiation. This acid works as catalyst for the polymerization. The connection of the