Pneumatic Disc Pump Application

TTP Ventus has teamed up with Sensirion to combine their SLF3x liquid flow sensor series with our Disc Pump Evaluation Kit to create a prototype microfluidics driver, highlighting the exceptional liquid flow control that can be achieved by combining our technologies. This approach suits a wide range of microfluidics applications, from IVD diagnostic instrumentation (including miniaturised systems for Point of Care) to droplet microfluidics.

The key features of the system:

High-precision, stable flow-rate control.
Large dynamic flow range (four orders of magnitude).
Smooth liquid flow – no pulsation or oscillation.
Rapid response to setpoint changes.
Highly compact implementation possible.
Pressure-driven flow approach supports reusable/disposable model where cross- contamination needs to be avoided.

5.1 Performance

Figure 2 shows a logarithmic step-function in flow rate over four orders of magnitude: 3, 30, 300 and 3000 μL/min. At each step, flow is held for 30 seconds to demonstrate the flow control precision and stability. The time required to transition between steps is less than 2 seconds.

What limits performance?

The maximum flow rate that can be achieved is determined by the maximum pneumatic pressure the pump can deliver, and a range of other factors including the liquid flow resistance through the system (e.g. as determined by the channel geometry and surface properties), the viscosity and surface tension of the fluid. TTP Ventus offers a range of pumps to suit your pressure requirements.

The minimum flow rate, in principle, should be zero, as Disc Pump has no stall speed and therefore has a near-infinite turn-down ratio. The resolution of the pump output is also ‘continuous’. In practice, both the minimum flow rate and flow rate resolution are likely to be determined by the limits of the flow sensor and the pump drive electronics, rather than by the pump itself.

System Components

  • TTP Ventus Disc Pump Evalutuation Kit, fitted in this example with a DP-S2-007 pump1.

  • Sensirion SLF3S-0600F flow sensor, offering a 0 to ±2000 μL/min measurement range2.

  • Liquid reservoir—we used an Elveflow Microfluidic Reservoir for 15 mL Falcon Tube - S

    (2 port) with the add-on fluidic fittings kit, but other reservoirs will work equally well.

  • Molex 151340602 cable assembly to connect flow sensor to the Evaluation Kit.

  • Optional: needle valve / bleed orifice between pump and reservoir (not shown in photo).

    This may be helpful for very low flow rate control and/or ability to stop liquid flow quickly, dependent on the specific system architecture.