Abstract:Sorting of particles such as cells is a critical process for many biomedical applications, and it is challenging to integrate it into an analytical microdevice. We report an effective and flexible dielectrophoresis (DEP)-based microfluidic device for continuous sorting of multiple particles in a microchannel. The particle sorter is composed of two components -a DEP focusing unit and a Movable DEP Trap (MDT). The trap is formed by an array of microelectrodes at the bottom of the channel and a transparent electrode plate placed at the top. The location of the trap is dependent on the configuration of voltages on the array and therefore is addressable. Flowing particles are first directed and focused into a single particle stream by the focusing unit. The streamed particles are then sorted into different fractions using the movable trap by rapidly switching the applied voltage. The performance of the sorter is demonstrated by successfully sorting microparticles in a continuous flow. The proposed DEP-based microfluidic sorter can be implemented in applications such as sample preparation and cell sorting for subsequent analytical processing, where sorting of particles is needed.
This paper presents a smart passive MR damper with fast-responsive characteristics for impact mitigation. The hybrid powering system of the MR damper, composed of batteries and self-powering component, enables the damping of the MR damper to be negatively proportional to the impact velocity, which is called rate-dependent softening effect. This effect can keep the damping force as the maximum allowable constant force under different impact speed and thus improve the efficiency of the shock energy mitigation. The structure, prototype and working principle of the new MR damper are presented firstly. Then a vibration platform was used to characterize the dynamic property and the self-powering capability of the new MR damper. The impact mitigation performance of the new MR damper was evaluated using a drop hammer and compared with a passive damper. The comparison results demonstrate that the damping force generated by the new MR damper can be constant over a large range of impact velocity while the passive damper cannot. The special characteristics of the new MR damper can improve its energy dissipation efficiency over a wide range of impact speed and keep occupants and mechanical structures safe.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.