Dynamic Observation of Retinal Response to Pressure Elevation in a Microfluidic Chamber.

Dynamic observation of cell and tissue responses to elevated pressure could help our understanding of important physiological and pathological processes related to pressure-induced injury. Here, we report on a microfluidic platform capable of maintaining a wide range of stable operating pressures (30 to 200 mmHg) while using a low flowrate (2-14 μL/h) to limit shear stress. This is achieved by forcing flow through a porous resistance matrix composed of agarose gel downstream of a microfluidic chamber.

Rapid prototyping of cell culture microdevices using parylene-coated 3D prints.

Fabrication of microfluidic devices by photolithography generally requires specialized training and access to a cleanroom. As an alternative, 3D printing enables cost-effective fabrication of microdevices with complex features that would be suitable for many biomedical applications. However, commonly used resins are cytotoxic and unsuitable for devices involving cells.

Bidirectional Modulation of Contact Thermal Resistance between Boron Nitride Nanotubes from a Polymer Interlayer.

Enhancing the thermal conductivity of polymer composites could improve their performance in applications requiring fast heat dissipation. While significant progress has been made, a long-standing issue is the contact thermal resistance between the nanofillers, which could play a critical role in the composite thermal properties. Through systematic studies of contact thermal resistance between individual boron nitride nanotubes (BNNTs) of different diameters, with and without a poly(vinylpyrrolidone) (PVP) interlayer, we show that the contact thermal resistance between bare BNNTs is largely determined by reflection of ballistic phonons.

Contact Thermal Resistance between Silver Nanowires with Poly(vinylpyrrolidone) Interlayers.

Various nanofillers have been adopted to enhance the thermal conductivity of polymer nanocomposites. While it is widely believed that the contact thermal resistance between adjacent nanofillers can play an important role in limiting thermal conductivity enhancement of composite materials, lack of direct experimental data poses a significant challenge to perceiving the effects of these contacts. This study reports on direct measurements of thermal transport through contacts between silver nanowires (AgNWs) with a poly(vinylpyrrolidone) (PVP) interlayer.

Electrical and Thermal Transport through Silver Nanowires and Their Contacts: Effects of Elastic Stiffening.

Silver nanowires have been widely adopted as nanofillers in composite materials used for various applications. Electrical and thermal properties of these composites are critical for proper device operation, and highly depend on transport through the nanowires and their contacts, yet studies on silver nanowires have been limited to one or two samples and no solid data have been reported for individual contacts. Through systematic measurements of silver nanowires of different sizes, we show that the Lorenz number increases with decreasing wire diameter and has a higher value at wire contacts.

The relationship between the Young's modulus and dry etching rate of polydimethylsiloxane (PDMS).

Polydimethylsiloxane (PDMS) has been the pivotal materials for microfluidic technologies with tremendous amount of lab-on-a-chip devices made of PDMS microchannels. While molding-based soft-lithography approach has been extremely successful in preparing various PDMS constructs, some complex features have to been achieved through more complicated microfabrication techniques that involve dry etching of PDMS. Several recipes have been reported for reactive ion etching (RIE) of PDMS; however, the etch rates present large variations, even for the same etching recipe, which poses challenges in adopting this process for device fabrication.

Thermal transport in electrospun vinyl polymer nanofibers: effects of molecular weight and side groups.

Understanding and enhancing thermal transport in polymers is of great importance, and is necessary to enable next-generation flexible electronics, heat exchangers, and energy storage devices. Over the past several decades, significant enhancement of the thermal conductivity of polymeric materials has been achieved, but several key questions related to the effects of molecular structure on thermal transport still remain. By studying a series of electrospun vinyl polymer nanofibers, we investigate the relationship between thermal conductivity and both molecular chain length and side group composition.