PMC

(a) The 3D and (b) 2D schematics of the operation principle using driving pressure by centrifugal force, , or vacuum-driven pressure, . The centrifugal pressure allows the sample to be driven in a one-way direction, while the vacuum-driven force can be used for various directions to drag the sample without any rotation. To switch the dominant forces between centrifugal force and vacuum-driven force to drive samples, the fluidic passage should be wisely designed. For instance, if we let the liquid sample go through the open chamber and the closed chamber one after another, we can make the situation to let the sample driven by centrifugal force (with a rotation) and the vacuum-driven force one after another. (c) The comparison between the centrifugal flows and the vacuum-driven flows in each dead-end and open-end channel. The centrifugal pressure requires an open-end channel to drive a sample, while the vacuum-driven pressure requires a dead-end channel to drive a sample. In the proposed device, a dominant force is switched between the centrifugal force and the vacuum-driven force. is a rotational speed.

The curvature and centrifugal force vectors at cross sections 3 and 4.

Top: Rotation in the intra-ventricular flow-field can generate a more or less vigorous scouring (tractive shear) of the endocardium lining the chamber. Bottom: Under the action of centripetal and centrifugal forces associated with RV/LV rotatory diastolic flow, the endocardium and other wall components get deformed, akin to a ball squeezed between one’s palms. This dynamic interplay has not been previously recognized in the literature; it and its disturbances are likely to have intriguing epigenetic actions affecting cardiac function and adaptations, acting concurrently with the vortex-induced shear (Top), as summarized in the Middle. Middle: Myocardial cells (endocardium, myocytes, fibroblasts) can move, change shape, and switch genes on and off in response to changes in hydrodynamic shear and “squeeze” (see discussion in text).

(a) Normally closed configuration of the capillary wax valve. It can be switched to open mode by melting the wax plug blocking the channel (using a laser) and spinning the disc to flow the molten wax plug downstream, clearing the channel to open the fluidic channel. (b) The switch from normally open to closed configuration is achieved by melting the ferrowax in the wax chamber using a laser. Under the action of the capillary force, the molten wax flows into the valving channel and seals it, thus switching the valve from normally open to closed configuration. With enough wax in the wax chamber, this process is repeatable. (c) Normally closed configuration of the magnetic wax valve. It can be switched to open by melting the wax plug blocking the channel and the wax reservoir (laser/heating) and moving the wax with the magnet out of the channel, clearing the channel and opening the valve from normally closed to open configuration. (d) The switch from normally open to closed configuration (magnet wax valve) is achieved by melting the ferrowax in the wax chamber (using laser) and moving the wax with the magnet into the channel. This reversibly changes the configuration from normally open to closed configuration. Yellow arrows show the direction of the magnetic force.