23 research outputs found
Diffusion-Dominated Pinch-Off of Ultralow Surface Tension Fluids
We study the breakup of a liquid thread inside another liquid at different
surface tensions. In general, the pinch-off of a liquid thread is governed by
the dynamics of fluid flow. However, when the interfacial tension is ultralow
(2 to 3 orders lower than normal liquids), we find that the pinch-off dynamics
can be governed by bulk diffusion. By studying the velocity and the profile of
the pinch-off, we explain why the diffusion-dominated pinch-off takes over the
conventional breakup at ultralow surface tensions.Comment: 7 pages, 5 figures. Published versio
Additive Manufacturing in Customized Medical Device
The long-established application of rapid prototyping in additive manufacturing (AM) has inspired a revolution in the medical industry into a new era, in which the clinical-driven development of the customized medical device is enabled. This transformation could only be sustainable if clinical concerns could be well addressed. In this work, we propose a workflow that addresses critical clinical concerns such as translation from medical needs to product innovation, anatomical conformation and execution, and validation. This method has demonstrated outstanding advantages over the traditional manufacturing approach in terms of form, function, precision, and clinical flexibility. We further propose a protocol for the validation of biocompatibility, material, and mechanical properties. Finally, we lay out a roadmap for AM-driven customized medical device innovation based on our experiences in Hong Kong, addressing problems of certification, qualification, characterization of three dimensional (3D) printed implants according to medical demands
Droplet Formation by Rupture of Vibration-Induced Interfacial Fingers
By
imposing vibration to a core-annular flow of an aqueous two-phase
system (ATPS) with ultralow interfacial tension, we observe a liquid
finger protruding from the interface of an expanding jet. We find
that the protruded finger breaks up only when its length-to-width
ratio exceeds a threshold value. The breakup follows a constant wavelength-to-width
ratio that is consistent with that of breakup under Rayleigh-Plateau
instability. The mechanism is applicable to aqueous two-phase systems
with a large range of viscosity ratios. The protruded finger can break
up into small droplets that are monodisperse in size, controllable
in generation frequency under a wide range of flow rates. This work
suggests a way to generate small water–water droplets with
high monodispersity and production rate from a single nozzle
Engineering an Enhanced EGFR Engager: Humanization of Cetuximab for Improved Developability
The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase whose proliferative effects can contribute to the development of many types of solid tumors when overexpressed. For this reason, EGFR inhibitors such as cetuximab can play an important role in treating cancers such as colorectal cancer and head and neck cancer. Cetuximab is a chimeric monoclonal antibody containing mouse variable regions that bind to EGFR and prevent it from signaling. Although cetuximab has been used clinically since 2004 to successfully control solid tumors, advances in protein engineering have created the opportunity to address some of its shortcomings. In particular, the presence of mouse sequences could contribute to immunogenicity in the form of anti-cetuximab antibodies, and an occupied glycosylation site in FR3 can contribute to hypersensitivity reactions and product heterogeneity. Using simple framework graft or sequence-/structure-guided approaches, cetuximab was humanized onto 11 new frameworks. In addition to increasing humanness and removing the VH glycosylation site, dynamic light scattering revealed increases in stability, and bio-layer interferometry confirmed minimal changes in binding affinity, with patterns emerging across the humanization method. This work demonstrates the potential to improve the biophysical and clinical properties of first-generation protein therapeutics and highlights the advantages of computationally guided engineering
Perturbation-induced droplets for manipulating droplet structure and configuration in microfluidics
Emergence of Droplets at the Nonequilibrium All-Aqueous Interface in a Vertical Hele-Shaw Cell
The interfacial phenomena
at liquid–liquid interfaces remain
the subject of constant fascination in science and technology. Here,
we show that fingers forming at the interface of nonequilibrium all-aqueous
systems can spontaneously break into an array of droplets. The dynamic
formation of droplets at the water–water (w/w) interface is
observed when a less dense aqueous phase, for instance, the dextran
solution, is placed on a denser aqueous phase, the polyethylene glycol
solution, in a vertical Hele-Shaw cell. Because of the gradual diffusion
of water from the upper phase into the lower phase, a dense layer
appears at the nonequilibrium w/w interface. As a result, a periodic
array of fingers emerge and sink. Remarkably, these fingers break
up and an array of droplets are emitted from the interface. We characterize
the wavelength of fingering by measuring the average distance between
the dominant fingers. By varying the initial concentrations of the
two nonequilibrium aqueous phases, we identify experimentally a phase
diagram with a wide parameter space in which finger breaking occurs.
Finally, plenty of droplets, spontaneously formed when one phase is
continuously deposited onto another aqueous phase, further confirm
the robustness of our experimental results. Our work suggests a simple
yet efficient approach with a potential upscalability to generate
all-aqueous droplets
Emergence of Droplets at the Nonequilibrium All-Aqueous Interface in a Vertical Hele-Shaw Cell
The interfacial phenomena
at liquid–liquid interfaces remain
the subject of constant fascination in science and technology. Here,
we show that fingers forming at the interface of nonequilibrium all-aqueous
systems can spontaneously break into an array of droplets. The dynamic
formation of droplets at the water–water (w/w) interface is
observed when a less dense aqueous phase, for instance, the dextran
solution, is placed on a denser aqueous phase, the polyethylene glycol
solution, in a vertical Hele-Shaw cell. Because of the gradual diffusion
of water from the upper phase into the lower phase, a dense layer
appears at the nonequilibrium w/w interface. As a result, a periodic
array of fingers emerge and sink. Remarkably, these fingers break
up and an array of droplets are emitted from the interface. We characterize
the wavelength of fingering by measuring the average distance between
the dominant fingers. By varying the initial concentrations of the
two nonequilibrium aqueous phases, we identify experimentally a phase
diagram with a wide parameter space in which finger breaking occurs.
Finally, plenty of droplets, spontaneously formed when one phase is
continuously deposited onto another aqueous phase, further confirm
the robustness of our experimental results. Our work suggests a simple
yet efficient approach with a potential upscalability to generate
all-aqueous droplets
Emergence of Droplets at the Nonequilibrium All-Aqueous Interface in a Vertical Hele-Shaw Cell
The interfacial phenomena
at liquid–liquid interfaces remain
the subject of constant fascination in science and technology. Here,
we show that fingers forming at the interface of nonequilibrium all-aqueous
systems can spontaneously break into an array of droplets. The dynamic
formation of droplets at the water–water (w/w) interface is
observed when a less dense aqueous phase, for instance, the dextran
solution, is placed on a denser aqueous phase, the polyethylene glycol
solution, in a vertical Hele-Shaw cell. Because of the gradual diffusion
of water from the upper phase into the lower phase, a dense layer
appears at the nonequilibrium w/w interface. As a result, a periodic
array of fingers emerge and sink. Remarkably, these fingers break
up and an array of droplets are emitted from the interface. We characterize
the wavelength of fingering by measuring the average distance between
the dominant fingers. By varying the initial concentrations of the
two nonequilibrium aqueous phases, we identify experimentally a phase
diagram with a wide parameter space in which finger breaking occurs.
Finally, plenty of droplets, spontaneously formed when one phase is
continuously deposited onto another aqueous phase, further confirm
the robustness of our experimental results. Our work suggests a simple
yet efficient approach with a potential upscalability to generate
all-aqueous droplets
Emergence of Droplets at the Nonequilibrium All-Aqueous Interface in a Vertical Hele-Shaw Cell
The interfacial phenomena
at liquid–liquid interfaces remain
the subject of constant fascination in science and technology. Here,
we show that fingers forming at the interface of nonequilibrium all-aqueous
systems can spontaneously break into an array of droplets. The dynamic
formation of droplets at the water–water (w/w) interface is
observed when a less dense aqueous phase, for instance, the dextran
solution, is placed on a denser aqueous phase, the polyethylene glycol
solution, in a vertical Hele-Shaw cell. Because of the gradual diffusion
of water from the upper phase into the lower phase, a dense layer
appears at the nonequilibrium w/w interface. As a result, a periodic
array of fingers emerge and sink. Remarkably, these fingers break
up and an array of droplets are emitted from the interface. We characterize
the wavelength of fingering by measuring the average distance between
the dominant fingers. By varying the initial concentrations of the
two nonequilibrium aqueous phases, we identify experimentally a phase
diagram with a wide parameter space in which finger breaking occurs.
Finally, plenty of droplets, spontaneously formed when one phase is
continuously deposited onto another aqueous phase, further confirm
the robustness of our experimental results. Our work suggests a simple
yet efficient approach with a potential upscalability to generate
all-aqueous droplets