Chung-Yuen Hui

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In vitro, animal cells are mostly cultured on a gel substrate. It was recently shown that substrate stiffness affects cellular behaviors in a significant way, including adhesion, differentiation, and migration. Therefore, an accurate method is needed to characterize the modulus of the substrate. In situ microscopic measurements of the gel substrate modulus(More)
We measured the force required to peel single-stranded DNA molecules from single-crystal graphite using chemical force microscopy. Force traces during retraction of a tip chemically modified with oligonucleotides displayed characteristic plateaus with abrupt force jumps, which we interpreted as a steady state peeling process punctuated by complete(More)
Microcontact printing (microCP) is an effective way to generate micrometer- or submicrometer-sized patterns on a variety of substrates. However, the fidelity of the final pattern depends critically on the coupled phenomena of stamp deformation, fluid transfer between surfaces, and the ability of the ink to self-assemble on the substrate. In particular,(More)
Elasticity analysis and finite element simulations are carried out to study the strength of an elastic fibrillar interface. The fibrils are assumed to be in perfect contact with a rigid substrate. The adhesive interaction between the fibrils and the substrate is modelled by the Dugdale-Barenblatt model (DB). The condition for a fibrillar interface to be(More)
We present a synthetic adaptation of the fibrillar adhesion surfaces found in nature. The structure consists of protruding fibrils topped by a thin plate and shows an experimentally measured enhancement in adhesion energy of up to a factor of 9 over a flat control. Additionally, this structure solves the robustness problems of previous mimic structures and(More)
Two important putative functions of the fibrillar contact interfaces commonly found in lizards and insects are to provide contact compliance and enhanced adhesion. To explore the question of whether a fibrillar architecture inherently enhances adhesion, we constructed model structures consisting of thin sheets of poly(vinyl butyral) (PVB) bonded on one of(More)
In native states, animal cells of many types are supported by a fibrous network that forms the main structural component of the ECM. Mechanical interactions between cells and the 3D ECM critically regulate cell function, including growth and migration. However, the physical mechanism that governs the cell interaction with fibrous 3D ECM is still not known.(More)
A film-terminated fibrillar interface has been shown to result in significant enhancement of adhesion and static friction compared to a flat control. This enhancement increases with interfibril spacing. In this, the first of a two-part study, by studying the effect of rate on adhesion and static friction, we show that both adhesion and static friction(More)
A physical model consisting of an axisymmetrical jet in a rigid plexiglass pipe was used to study the flow and pressure fluctuations downstream from an aortic stenosis. The fluctuating velocity components, u and v, at several locations in the steady liquid jet were measured using a laser Doppler anemometer system. Simultaneous wall pressure fluctuations(More)
The stress field near the tip of a crack in a plate subjected to membrane and bending loads and undergoing large deflections, is investigated by performing an asymptotic analysis in the context of von Karman plate theory. It is demonstrated that the character of the near tip fields is identical to those of the linear plate theory. However, the determination(More)