The following links provide synopses of Center research projects.

• Calculation of On- and Off-rates from Association and Dissociation Curves
  

  A microfluidic “button” consisting of a valve actuated by pressure in the control layer of a PDMS device can be used to trap interactions. Using the system for an out-of-equilibrium measurement establishes association and dissociation curves: With the first interacting partner (bait) immobilized on glass substrate using an epitope tag antibody, the second interaction partner (prey) is flowed in. Then the system is subjected to repeated rounds of lifting the button for a set time followed by flowing more prey to maintain a constant, known concentration, and the amount of prey bound is measured fluorescently.
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• Computational Modeling of a Droplet Impingement on Substrate
  

  Droplet impingement behavior on substrate is critical in determining the configuration of the underlying feature pattern being developed. We have investigated various parameters including initial drop velocity, viscosity of the liquid, drop contact angle with substrate to observe the drop propagation, impingement and stabilization.
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• Direct-Write Assembly of 3D Hydrogel Scaffolds
  

  Here we report the fabrication of 1D and 3D micro-periodic hydrogel scaffolds by directwrite assembly of an acrylamide-based ink. For the first time, we combine direct ink writing with in-situ photopolymerization to obtain hydrogel scaffolds with micron-sized features.
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• First Integration of VCSEL Optical Sensing in Optofluidic Microsystem
  

  We have achieved the first intimate integration of vertical-cavity surface- emitting lasers with a network of microfluidic channels to form a compact microfluidic microsystem. The integration of optics and fluidics opens new opportunities for the creation of compact biomedical diagnostic microsystems.
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• Generating Student Excitement for Manufacturing
  

  Light from a data projector is shone at a beaker containing a photoactive polymer. The polymer solidifies where it is exposed to the light, creating a cross-section of the object. The cross-section is lowered into the beaker, allowing fresh polymer to flow over the top. By synchronizing a series of PowerPoint images with stepping of the elevator, the students can “print” a 3-D object, plane by plane.
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• High Performance Motion Control via Time varying Norm Optimal ILC
  

  High performance motion control is crucial to nanoscale manufacturing. In addition to motion planning, sensor & actuator selection, and mechanism design, it is imperative that control algorithms be developed that are able to maximize the positioning performance for motion stages. We have been developing advanced motion tracking algorithms based on Iterative Learning Control.
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• Molecular Confinement Accelerates Nanometer-Scale Squeeze Flow of Entangled Polymer Films
  

  At the nanoscale, processes such as nanoimprint lithography squeeze polymers to form patterns during the manufacture of semiconductor devices, organic electronics and optics. Thin films of polymer are important in adhesives, coatings and lubricants.
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• Nano-Microfluidic Approach to Inkjet Nozzles
  

  Non-contact solution printing methods such as thermal or piezoelectric inkjet are attractive due to their compatibility with various materials and substrates. Interests in their applications in electronics and biotechnology, where requirements on resolution can be demanding, have grown rapidly in recent years. We have successively developed an electrohydrodynamic jet (e-jet) printing method in which diverse functional organic / inorganic inks (single walled carbon nanotubes, nanoparticles, conducting / insulating polymers, etc) can be ejected with submicron printing resolutions.
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• Nanoscale Patterns of Oligonucleotides Formed by Electrohydrodynamic Jet Printing with Applications in Biosensing and Nanomaterials Assembly
  

  The widespread use of DNA in microarrays for applications in biotechnology, combined with its promise in programmed nanomaterials assembly, unusual electronic devices, and other areas has created interest in methods for patterning DNA with high spatial resolution. Techniques based on thermal or piezoelectric inkjet printing are attractive due to their noncontacting nature and their compatibility with diverse materials and substrate types; their modest resolution (i.e., 10?20 ?m) represents a major limitation for certain systems.
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• Optical Metrology for Nano-CEMMS
  

  It has been shown that optical interferometry is sensitive to sub-wavelength scatterers . Furthermore, an approach has been proposed to estimate the polarizability of a single anisotropic nanoparticle through the use of coherent confocal microscopy, polarization diversity, and appropriate modeling.
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• Orientation-Driven Water Flow in Nanotubes
  

  Bidirectional single file water transport in a carbon nanotube is known to occur in “bursts” in short nanotubes. During the last year, we have shown that in long carbon nanotubes, when the orientation of the water molecules is maintained along one direction, a net water transport along that direction can be attained due to coupling between rotational and translational motions.
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• SOI-MEMS Positioning Stages with Active Cantilevers
  

  We have successfully developed a new class of MEMS-scale machines for manufacturing and metrology purposes. These devices are capable of controlled motion in the X, Y and Z directions, giving use out of plane motion capabilities.
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• Superionic Electrochemical Nanoimprinting
  

  Nanoscale metallic features are the core of a wide variety of key applications such as nano-electronic, photonic and nano-electromechanical devices, as well as nanoscale chemical sensors and transducers. However, the fabrication of them has relied on indirect approaches like damascene processes and electrochemical micro-machining (ECM) which are generally expensive and complex.
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• Ultrafiltration of Biological Samples for Fraction Through Multiple Nanocapillary Array Membranes Alternately Sandwiched Between Microfluidic Channels
  

  The combination of microfluidics and nanofluidics enables a range of molecular manipulations for mass/volume-limited applications, critical for nanomanufacturing systems and to create a sensitive analytical measurement platform. Molecular sizing and filtration of samples is one such capability. As the diameter of nanocapillaries are comparable to the sizes of larger molecules such as proteins and dextrans, we can selectively hinder or transport analytes to fractionate a mixture.
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