A Theoretical Model of a Molecular-Motor-Powered Pump

The motion of a cylindrical bead in a fluid contained within a two-dimensional channel is investigated using the boundary element method as a model of a biomolecular-motor-powered microfluidics pump. The novelty of the pump lies in the use of motor proteins (kinesin) to power the bead motion and the few moving parts comprising the pump. The performance and feasibility of this pump design is investigated using two model geometries: a straight channel, and a curved channel with two concentric circular walls. In the straight channel geometry, it is shown that increasing the bead radius relative to the channel width, increases the flow rate at the expense of increasing the force the kinesins must generate in order to move the bead. Pump efficiency is generally higher for larger bead radii, and larger beads can support higher imposed loads. In the circular channel geometry, it is shown that bead rotation modifies the force required to move the bead and that shifting the bead inward slightly reduces the required force. Bead rotation has a minimal effect on flow rate. Recirculation regions, which can develop between the bead and the channel walls, influence the stresses and force on the bead. These results suggest this pump design is feasible, and the kinesin molecules provide sufficient force to deliver pico- to atto- l/s flows.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44478/1/10544_2005_Article_6168.pd

A parametric study of ethylene-fueled scramjet combustion

Ignition-delay distances for ethylene fuel injected into a supersonic combustor are modeled for jet-in-crossflow and shear-layer fuel-injection schemes using analytical models for entrainment and mixing, coupled with detailed chemical-kinetics simulations. Ignition delay distances are calculated for a two-dimensional parameter space of assumed vehicle flight Mach number and fuel-preheat stagnation temperature. The sensitivity of the ignition delays to these parameters is compared and discussed for the two fuel-injection schemes

Active directional control of biomolecular motor-driven microtubules with electric fields

We demonstrate active directional control of microtubule translocation in microfluidic chambers with E-fields. An E-field produces enough electrophoretic force on the leading end of moving microtubules to bend them towards the anode, such that the entire microtubule quickly aligns with the E-field. With time-varying E-field control, we are able to direct microtubules along arbitrary paths; as an example we direct a microtubule to translocate in a circle about 30 ??m in diameter

Biomolecular motor-driven selective binding and concentrating of protein analytes

We successfully demonstrated a biomolecular motor-driven microfluidic device that can detect target molecules from an analyte stream and then preconcentrate them at a horseshoe-shaped collector. This device removed approximately a few thousand molecules per second from the analyte stream, and the fluorescent signal from collected, labeled molecules at the collector increases up to five orders of magnitude within an hour