Abstract: A closure for a sample tube comprises a reaction vessel. The reaction vessel comprises: at least one microfluidic mixing channel having an inlet and an outlet; at least one reaction chamber in fluid communication with the inlet and the outlet; an inlet chamber proximate the inlet of the at least one microfluidic mixing channel for introducing a portion of a sample solution from the sample tube into the at least one reaction chamber under hydrostatic pressure; and a diffusion-control feature for limiting egress of fluid from the outlet such that the portion of the sample solution introduced to the at least one reaction chamber is partitioned from the rest of the sample solution.

Abstract: A system for producing microbeads includes a microfluidic device defining a supply channel and a shearing channel, a microbead precursor material disposed in the supply channel, a carrier fluid disposed in the shearing channel, and a pressure distribution system fluidly connected to each of the supply channel and the shearing channel to control at least relative pressures of the microbead precursor material and the carrier fluid. The supply channel includes a check valve adapted to be subjected to a bias pressure that is sufficient to close the check valve to flow of microbead precursor material when a supply pressure of the microbead precursor material is below a threshold pressure and is open to flow of the microbead precursor material when the supply pressure of the microbead precursor material is greater than the threshold pressure.

Abstract: A system for producing microbeads includes a microfluidic device defining a supply channel and a shearing channel, a microbead precursor material disposed in the supply channel, a carrier fluid disposed in the shearing channel, and a pressure distribution system fluidly connected to each of the supply channel and the shearing channel to control at least relative pressures of the microbead precursor material and the carrier fluid. The supply channel includes a check valve adapted to be subjected to a bias pressure that is sufficient to close the check valve to flow of microbead precursor material when a supply pressure of the microbead precursor material is below a threshold pressure and is open to flow of the microbead precursor material when the supply pressure of the microbead precursor material is greater than the threshold pressure.