Shock-free ion transmission from atmospheric pressure to a microelectromechanical system (MEMS)-based mass spectrometer has been achieved using micro-engineered nickel skimmers. The signal level has increased 70-fold compared with a previous configuration in which the skimmer did not sample the supersonic flow. The skimmers are formed by electroplating internal surfaces of anisotropically etched, pyramidal holes in (100) silicon. Etching from the reverse of the wafer exposes free-standing, open-ended skimmers supported by remaining silicon. High-resolution schlieren imaging has been used to visualise gas flow within the interface. Signal enhancement and increased gas throughput are observed when the skimmer attaches to the supersonic gas expansion via oblique shocks. The silicon back wall interacts with the flow field, causing the free jet Mach disc to evolve into a bowl-shaped surface shock whose position asymptotically approaches a stand-off separation as the interface pressure decreases. Ideally, the skimmer entrance should be located approximately midway between the inlet and the back wall. This development should allow a sensitivity increase in MEMS mass spectrometers using pumps of moderate capacity.

使用微设计的镍撇油器已经实现了从大气压到基于微机电系统（MEMS）的质谱仪的无冲击离子传输。与以前的分离器不对超音速流进行采样的配置相比，信号电平已增加了70倍。撇油器是通过在（100）硅中电镀各向异性蚀刻的金字塔形孔的内表面而形成的。从晶圆背面进行蚀刻会暴露出残留的硅支撑的独立式开放式撇油器。高分辨率schlieren成像已用于可视化界面内的气流。当撇渣器通过倾斜冲击附着在超音速气体膨胀装置上时，会观察到信号增强和气体通过量增加的情况。硅后壁与流场相互作用，导致自由射流马赫圆盘演变成碗形的表面冲击，当界面压力降低时，其位置渐近地接近隔离距离。理想情况下，撇渣器的入口应位于入口和后壁之间的大约中间位置。这种发展应允许使用中等容量的泵提高MEMS质谱仪的灵敏度。