摘要
Automatic and programmable pressure controllers are critical to miniature pneumatic systems employing pressurized air to transport and manipulate fluidic samples. We have successfully demonstrated (1) a digital pressure control scheme containing active converters and passive regulators that can be readily miniaturized and automated, (2) a 3D PDMS fabrication and integration scheme that can realize on-chip and self-contained pressure controllers for miniature pneumatic systems, and (3) pressure controllers that can switch downstream air pressure between specific levels on demand. In the proposed pressure controller, a regulator is utilized to yield a steady air output, whose pressure is determined by a serial digital-to-analog converter and switched between specific levels on demand. More specifically, a converter guided diaphragm bypasses a certain portion of the input air to reduce and stabilize the output pressure. In the prototype demonstration, PDMS structures were duplicated using 3D-printed molds, bonded and integrated on chip or into self-contained pressure controllers of 25 cm 3 in volume. Four-digit converters were employed to realize pressure output at 16 evenly spaced levels. The errors of the measured output pressure were less than 2.4 % of the target pressure while the fluctuations were below 1.2 %. It was also demonstrated that the switching time between pressure levels was less than 0.3 s when digital valves operating at 10 Hz were utilized. As such, the demonstrated miniature pressure controllers could replace their bulky/costly counterparts, and automatic and programmable control of pneumatically driven systems could potentially be realized.