An electronic device locking system, comprising a display member coupled to a base member to enable variable positioning of the display member relative to the base member and a post engagable with a latch to secure the display member in a fixed position relative to the base member. The machine is suitable for kidney failure treatments, such as hemofiltration and hemodiafiltration. A difference detector compares a monitor signal level with a predetermined reference level, and then outputs wavelength information to a second optical transmission path. The controller is electrically coupled with the actuator and is configured to facilitate movement of the actuator from the retracted position to the deployed position in response to detection of a collision. In some embodiments, such systems, methods, and devices are used to combine fluids while removing gaseous bubbles.