A nanoscale spring-loaded valve actuated by colloidal forces

A spring-loaded valve analogue based on utilization of colloidal forces between two nano-particles in a confined domain is proposed. The governing principle of the proposed valve is that altering the surface potential of the walls of a confining cylindrical capillary can modulate the electrostatic component of the total colloidal force between two particles. This colloidal force can function as a restoring force of a springloaded valve acting against the external forces exerted by the fluid. Dynamic simulations of the valve actuation are presented, showing the motion of the microvalve components under the influence of different wall surface potentials and external forces. The simulations indicate that colloidal forces can be utilized effectively to actuate the valve under typical external loadings anticipated in microscale fluidic channels.