Active manipulation of trapping performance by elastic deformation of the polydimethylsiloxane (PDMS) device. (
a) Sketch of the experimental setup using a precision screw to apply an axial compression force onto the PDMS device. ( b) Magnified area of ( a), illustrating the height change of the nanofluidic channel when a compression force is applied to the device. ( c) Active manipulation of the trapping strength of a d=100 nm Au NP trapped in a w p=250 nm circular pocket at an initial nanofluidic channel height of h c,0=160 nm and a pocket depth of h p=100 nm. In the top graph the radial fluctuations r of the particle are plotted as a function of time t at different applied pressures. The corresponding MSDs are shown in the middle graph as a function of the lag time Δ t. The obtained radial trap stiffnesses from the MSDs are plotted in the lower graph as a function of the applied compression pressure P. Increasing the compression pressure of to the PDMS results in a nanofluidic channel height reduction and thus higher trapping strength. ( d) Radial trap stiffness fits on simulations of the electrostatic energy along the axial energy minimum for a point charge of q=−258 e (100 nm particle) for different nanofluidic channel heights h c. ( e) Comparison of measured and simulated values of the radial trap stiffness k r as a function of applied compression pressure P and nanofluidic channel height h c.