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When attempting to integrate single-molecule fluorescence microscopy with microfabricated devices such as microfluidic channels, fabrication constraints may prevent using traditional coverslips. Instead, the fabricated devices may require imaging through material with a different thickness or index of refraction. Altering either can easily reduce the quality of the image formation (measured by the Strehl ratio) by a factor of 2 or more, reducing the signal-to-noise ratio accordingly. In such cases, successful detection of single-molecule fluorescence may prove difficult or impossible. Here we provide software to calculate the effect of non-design materials upon the Strehl ratio or ensquared energy and explore the impact of common materials used in microfabrication.

Next generation pulsed power (NGPP) machines and accelerators require a better understanding of the materials used within the vacuum vessels to achieve lower base pressures (P << 10−5 Torr) and reduce the overall contaminant inventory while incorporating various dielectric materials which tend to be unfavorable for ultra-high vacuum (UHV) applications. By improving the baseline vacuum, it may be possible to delay the onset of impedance collapse, reduce current loss on multi-mega Amp devices, or improve the lifetime of thermionic cathodes, etc [3]. In this study, we examine the vacuum outgassing rate of Rexolite® (cross-linked polystyrene) and Kel-F® (polychlorotrifluoroethylene) as candidate materials for vacuum insulators [1]. These values are then incorporated into boundary conditions for molecular flow simulations using COMSOL Multiphysics® and used to predict the performance of a prototypical pulsed power system designed for 10−8 Torr operations.

Real-time monitoring of an individual’s physiologic state without constant observation by a healthcare professional necessitates the construction of an autonomous remote diagnostic device that is capable of performing a wide range of diagnostic functions. For many applications, assessing the immediate physiologic state of an individual as he or she is continuously exposed to diverse environments would require complex dynamic chemical processing scenarios that are capable of real time readouts. We seek to answer these problems by combining in vivo microneedle platforms with multifunctional lab-on-chip electrode arrays that are capable of detecting a wide variety of relevant biomarkers. The results presented here provide an important proof-of-concept demonstration of integration of microneedles with a microchip platform containing fluidic channels and electrode transducers. As shown by immunoassay detection of myoglobin and troponin, such a device may be used to extract interstitial fluid and monitor biologically important molecules.

Laser micromachining is becoming a common method for fabrication of microstructured medical devices. Developments in pulsed laser technology have made it possible to achieve precision machining of sub-micrometer features with minimal damage to the surrounding material. Several aspects of laser micromachining, including machining methods, types of lasers used in micromachining, and laser-material interaction, are discussed in this article. Biomedical applications of laser micromachining are also reviewed. The ablation behavior of silicon was examined as a function of laser energy, aperture, and repetition rate. In vitro studies showed that microscale grooves on silicon substrates may be used to orient human aortic vascular smooth muscle cells. We anticipate that the use of laser micromachining for modifying medical and dental devices will become more significant over the coming years.

Electrospun scaffolds have been used extensively for tissue engineering applications due to the simple processing scheme and versatility. However, many additional benefits can be imparted to these materials via post-processing techniques. Specifically the addition of structured pores on the micro-scale can offer a method to enable patterned cell adhesion, enhanced diffusional properties, and/or guide vascular infiltration upon implantation in vivo. In this study, we laser ablated electrospun poly(L: -lactic acid) (PLA) scaffolds and assessed the ablation process and cellular interaction by examining human adipose-derived stem cell (hASC) viability and proliferation on laser micro-machined scaffolds. Laser ablated pores of 150, 300, and 600 μm diameter were micro-machined through electrospun PLA scaffolds. Laser ablation parameters were varied and it was determined that the aperture and z-travel direction of the laser linearly correlated with the ablated pore diameter. To assess cytocompatibility of the micro-machined scaffolds, hASCs were seeded on each scaffold and cell viability was assessed on day 7. Human ASCs were able to adhere around the micro-machined features. DNA content was quantified on all scaffolds and it was determined that hASCs were able to proliferate on all scaffolds. The process of laser ablation could impart many beneficial features to electrospun scaffolds by increasing mass transport and mimicking micro-scale features and assisting in patterning of cells around micro-machined features.

In this study, carbon fiber electrodes were incorporated within a hollow microneedle array, which was fabricated using a digital micromirror device-based stereolithography instrument. Cell proliferation on the acrylate-based polymer used in microneedle fabrication was examined with human dermal fibroblasts and neonatal human epidermal keratinocytes. Studies involving full-thickness cadaveric porcine skin and trypan blue dye demonstrated that the hollow microneedles remained intact after puncturing the outermost layer of cadaveric porcine skin. The carbon fibers underwent chemical modification in order to enable detection of hydrogen peroxide and ascorbic acid; electrochemical measurements were demonstrated using integrated electrode-hollow microneedle devices.

In this study, biodegradable acid anhydride copolymer microneedles containing quantum dots were fabricated by means of visible light dynamic mask micro-stereolithography-micromolding and inkjet printing. Nanoindentation was performed to obtain the hardness and the Young's modulus of the biodegradable acid anhydride copolymer. Imaging of quantum dots within porcine skin was accomplished by means of multiphoton microscopy. Our results suggest that the combination of visible light dynamic mask micro-stereolithography-micromolding and inkjet printing enables fabrication of solid biodegradable microneedles with a wide range of geometries as well as a wide range of pharmacologic agent compositions.

The fabrication of defined surface topographies and three-dimensional structures is a challenging process for various applications, e.g. in photonics and biomedicine. Laser-based technologies provide a promising approach for the production of such structures. The advantages of femtosecond laser ablation and two-photon polymerization for microstructuring are well known. However, these methods cannot be applied to all materials and are limited by their high cost and long production time. In this study, biomedical applications of an indirect rapid prototyping, molding microreplication of laser-fabricated two- and three-dimensional structures are examined. We demonstrate that by this method any laser-generated surface topography as well as three-dimensional structures can be replicated in various materials without losing the original geometry. The replication into multiple copies enables fast and perfect reproducibility of original microstructures for investigations of cell–surface interactions. Compared to unstructured materials, we observe that microstructures have strong influence on morphology and localization of fibroblasts, whereas neuroblastoma cells are not negatively affected.