A data prefetching technique uses predefined prefetching criteria and prefetching models to identify and retrieve prefetched data. a spacing distance from the distal treatment section to an insulation facing-surface is less than a distance from the electrode facing-surface to the distal treatment section in the state that the abutment portion abuts on the distal treatment section. The client-side application can provide creation and design, rolodex, exchange, and update features. The reference layer is mounted on the sensor layer to form a reference vacuum cavity. By combining optical switches in both the vertical and horizontal directions, the resulting optical switching system handles switching in three dimensions. The second pull-up has a gate terminal coupled to a pull-up control terminal.