Tham khảo tài liệu 'the mems handbook mems applications (2nd ed) - m. gad el hak episode 2 part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 10-14 MEMS Applications Break-off of droplet 10V 50-85 ps FIGURE Droplet ejection sequence of HP 51626A printhead courtesy Tseng 1998c . FIGURE A printed vertical line smeared by satellite droplets courtesy Tseng 1998c . One way to eliminate puddle formation is to coat the chamber s outer surface with a nonwetting material. The inner surface of the chamber needs to remain hydrophilic for liquid refill. However even with this coating there is still no guarantee that puddle will not form. More research is underway to fully understand the mechanism in the puddle formation process. 2006 by Taylor Francis Group LLC Microdroplet Generators 10-15 20 ps 30 ps 40 ps 50 ps 60 ps 100 pm No satellite droplet 80 ps 100 ps 120 ps FIGURE Droplet ejection without satellite droplets courtesy Tseng 1998a . FIGURE Liquid puddle formation outside the micronozzles courtesy Tseng 1998d . 2006 by Taylor Francis Group LLC 10-16 MEMS Applications Material Issues Material issues including stress erosion durability and compatibility are very complex problems in the design of microdroplet generators. In the area of processing material compatibility stress and durability problems are commonly discussed. Material compatibility issues result from the processing temperature processing environment oxidation reactive gas etc. etching method used and adhesion ability stress issues usually concern the processing temperature as well as the doping condition material durability issues are due either to the material s intrinsic properties or the mechanical forces induced during the process . fluid flow force surface tension force vacuum forces or handling force . To eliminate the material issues much care needs to be taken in designing the process flow such as compensating for material stress during or after the fabrication process performing high-temperature processes before introducing the low temperature material finishing aggressive wet etching before metal film .
