Vorticity ratchet

Drift ratchet

We consider a silicon wafer, pierced by millions of identical pores with periodically varying diameters but without spatial inversion symmetry (ratchet profile). When a liquid is periodically pumped back and forth through the pores, our theory predicts a net transport of suspended micrometer-sized particles (drift ratchet). The direction of this particle current depends very sensitively on the ...

Deterministic microfluidic ratchet.

We present a deterministic, nonthermal ratchet where the trajectory of particles in a certain size range is not reversible when the sign of the pressure gradient is reversed at a low Reynolds number. This effect is produced by employing triangular rather than the conventional circular posts in an array that selectively displaces particles transported through the array. The ratchet irreversibly ...

The Ratchet Effect

OBJECTIVE To describe the previously unexamined association between admissions to hospital with chronic disease and changes in all-cause health service utilization over time. RESEARCH DESIGN A cohort study examining the population of Western Australia with hospitalizations for chronic disease from 2002 to 2010. A "rolling" clearance period is used to define "cardinal events," that is, a disea...

Experimental spin ratchet.

Spintronics relies on the ability to transport and use the spin properties of an electron rather than its charge. We describe a spin ratchet at the single-electron level that produces spin currents with no net bias or charge transport. Our device is based on the ground-state energetics of a single-electron transistor comprising a superconducting island connected to normal leads via tunnel barri...

Vorticity Capturing