Proportional Control Valves Integrated in Silicon Nitride Surface Channel Technology

We have designed and realized two types of proportional microcontrol valves in a silicon nitride surface channel technology process. This enables on-die integration of flow controllers with other surface channel devices, such as pressure sensors or thermal or Coriolis-based (mass) flow sensors, to obtain a proportional gas flow control system on a single chip. One valve design is implemented with inlet and outlet channels in the plane of the chip, which allows on-chip flow control between several fluidic components and allows up to 70 mgh^-1 of flow at 200 mbar. The other valve design operates out-of-plane between surface channels and a fluidic inlet, offering a flow range up to 1250 mgh^-1 at 600 mbar, smaller footprint, and low-leakage closure. Measured flow behavior agrees well with laminar flow models created for both valve types.