Dynamics of bubble formation in spontaneous microfluidic devices: Controlling dynamic adsorption via liquid phase properties

Capillary pressure-based measurement of dynamic interfacial tension in a spontaneous microfluidic sensor

“…2A), above which an increase in both bubble size and polydispersity can be observed, indicating the ‘dripping-jetting’ transition. 23 Although this regime is interesting for the extremely fast bubble formation, 2 and the rich behaviour of possible coalescence events and dripping-jetting transition, 23 it cannot be used for tensiometry due to absence of surfactant adsorption to a static meniscus.…”

“…2A. 23 In this case for droplets, the cross-over pressure is smaller than the Laplace transition pressure (c < b). This observation is most likely due to the much slower formation of droplets, which is caused by the markedly higher viscosity of the hexadecane than the air phase (i.e., a factor of approximately 200).…”

“…First, the EDGE tensiometer is simple and universal since no complex theoretical models or sophisticated calculations are needed. Second, the dynamic interfacial tension is linked to the adsorption lag timewhich can be approximated as droplet or bubble formation time in this devicewhich makes the method insensitive to produced droplet or bubble size and continuous phase properties (e.g., velocity and viscosity 23 ). Third, the adsorption lag time inherently covers the full decrease of dynamic interfacial tension from γ 0 to γ eq , as the low-pressure regime in this device is bounded by the Laplace pressures of the (nearly) empty and saturated interfaces.…”

“…SI 1A †). For whey protein isolate (WPI), the breakthrough pressure is much higher e.g., 1050 mbar for a high concentration of 10% wt WPI, 23 due to the higher equilibrium surface tension compared to that of SDS.…”