Fluid flow is a ubiquitous aspect of microfluidic systems.Gravity-driven flow is one microfluidic flow initiation and maintenance mechanism that is appealing because it is simple,requires no external power source,and ...Fluid flow is a ubiquitous aspect of microfluidic systems.Gravity-driven flow is one microfluidic flow initiation and maintenance mechanism that is appealing because it is simple,requires no external power source,and is easy to use.However,the driving forces created by hydraulic head differences gradually decrease during operation,resulting in decreasing flow rates that are undesirable in many microfluidic applications such as perfusion culture,droplet microfluidics,etc.Existing methods to maintain a constant gravity-driven flow either require additional control equipment,involve complex fabrication or operation,are incompatible with miniaturization,or introduce interfaces that lack robustness.Here we tackled those problems by introducing a 3D-printed compact hydraulic head auto-regulating module that automatically maintains a constant fluid level at the microfluidic inlet port without human intervention.Our module successfully maintained a constant hydraulic head for more than 24 h,with the operation time solely limited by the reservoir capacity.A comparison with the conventional gravity-driven flow demonstrated our device’s capability to produce a more stable flow over the perfusion period.Overall,our module creates a simple,robust solution to produce a stable flow rate in gravity-driven flow systems.The compactness of the design allows easy parallelization and compatibility with high-throughput applications,and the biocompatibility of the materials enables the device’s use with life science applications.展开更多
In this paper, we study and discuss the existence of multiple solutions of a class of non–linear elliptic equations with Neumann boundary condition, and obtain at least seven non–trivial solutions in which two are p...In this paper, we study and discuss the existence of multiple solutions of a class of non–linear elliptic equations with Neumann boundary condition, and obtain at least seven non–trivial solutions in which two are positive, two are negative and three are sign–changing. The study of problem (1.1): is based on the variational methods and critical point theory. We form our conclusion by using the sub–sup solution method, Mountain Pass Theorem in order intervals, Leray–Schauder degree theory and the invariance of decreasing flow.展开更多
基金supported by the NIH award 1R21NS120088the MIT School of Engineering Postdoctoral Fellowship Program for Engineering Excellence.
文摘Fluid flow is a ubiquitous aspect of microfluidic systems.Gravity-driven flow is one microfluidic flow initiation and maintenance mechanism that is appealing because it is simple,requires no external power source,and is easy to use.However,the driving forces created by hydraulic head differences gradually decrease during operation,resulting in decreasing flow rates that are undesirable in many microfluidic applications such as perfusion culture,droplet microfluidics,etc.Existing methods to maintain a constant gravity-driven flow either require additional control equipment,involve complex fabrication or operation,are incompatible with miniaturization,or introduce interfaces that lack robustness.Here we tackled those problems by introducing a 3D-printed compact hydraulic head auto-regulating module that automatically maintains a constant fluid level at the microfluidic inlet port without human intervention.Our module successfully maintained a constant hydraulic head for more than 24 h,with the operation time solely limited by the reservoir capacity.A comparison with the conventional gravity-driven flow demonstrated our device’s capability to produce a more stable flow over the perfusion period.Overall,our module creates a simple,robust solution to produce a stable flow rate in gravity-driven flow systems.The compactness of the design allows easy parallelization and compatibility with high-throughput applications,and the biocompatibility of the materials enables the device’s use with life science applications.
文摘In this paper, we study and discuss the existence of multiple solutions of a class of non–linear elliptic equations with Neumann boundary condition, and obtain at least seven non–trivial solutions in which two are positive, two are negative and three are sign–changing. The study of problem (1.1): is based on the variational methods and critical point theory. We form our conclusion by using the sub–sup solution method, Mountain Pass Theorem in order intervals, Leray–Schauder degree theory and the invariance of decreasing flow.
