A nanocup structure that mimics the Lycurgus cup effect enables nanoplasmonic spectroscopy to be used for colorimetric sensing, requiring only the naked eye or ordinary visible color photography. Enhanced optical transmission from the subwavelength cup structures couples with the localized surface plasmon from metal nanoparticles on the side walls of the cup, creating extraordinary sensitivity and visible color changes. Utility of the sensor for chemical imaging, biomolecular imaging, and integration to portable microfluidics devices for lab-on-chip applications has been demonstrated.
Strong electrostatic field, around positively charged gold nanoparticle surfaces, drags phosphorylated peptides down to the surface through the Coulombic interaction with the phosphate groups. The sub-nanometer scale intramolecular conformation changes are faithfully detected by surface-enhanced Raman spectroscopy and elucidated by molecular dynamics simulation.
In a simultaneous top-down and bottom-up nanofabrication approach called simultaneous plasma enhanced reactive ion synthesis and etching (SPERISE), the atomic addition and subtraction of nanomaterials are concurrently and precisely controlled on single and poly crystalline silicon wafers as well as amorphous silicon thin films. Demonstrated was ultrahigh-throughput, lithography-less nanomanufacturing of high-density, high-uniformity, light-trapping nanocone arrays.
A digital microfluidic CD device derived from conventional music or data CD was invented and only a standard CD drive in a personal computer is used for reading and decoding the quantitative cellular and molecular information in the minute-volume biofluid samples on CD. This is the first step towards creating a truly portable, low-cost and ubiquitously accessible device for biosensing and health diagnostics, especially in remote or impoverished areas.
The unique surface properties of the metallic nanocone array device enables high-density, high-uniformity nucleotide and peptide probe spotting beneficial to genomic and proteomic microarrays and surface molecular imaging of peptide substrates targeting kinase enzymes. The high-uniformity and repeatability of molecular depositions on the 'coffee stain'-free nanocone surface is confirmed by laser scanning fluorescence imaging and surface enhanced Raman imaging experiments.
Microfluidic device made entirely from a biopolymer with agricultural origin, zein - a corn protein, can be utilized as a disposable environment friendly microchip especially for agriculture applications, reducing the dependence on limited petroleum based polymer resources. The ease of fabrication and bonding and the flexibility and moldability of corn protein zein offer attractive possibilities for microfluidic device design and manufacturing.
Fluorescently labeled living cells, were imaged on the nanoplasmonic surface, three-dimensional fluorescence enhancements was observed for the cells. The detailed optical analysis showed the possibility of light coupling to resonance modes in the cell microcavity. This may offer opportunity to capture single molecular events in living cells, observe very early stage protein expressions soon after gene transfection, and discover new basic mechanisms in cytoskeletal dynamics.
The effect of a strong static local electric field due to the Schottky barrier at the metal-molecule junction on SERS is systematically investigated. It was found that a strong electrostatic built-in field at the metal-molecule junction can result in 2-4 more orders of enhancement in SERS. The study provides a viable explanation to the low repeatability of SERS experiments as well as the Raman peak shifts as observed in SERS and raw Raman spectra.
Quantitative monitoring of water conditions in a field is a critical ability for environmental science studies. We report the design, fabrication and testing of a low cost, miniaturized and sensitive electrochemical based nitrate sensor for quantitative determination of nitrate concentrations in water
samples. We have presented detailed analysis for the nitrate detection results using the miniaturized sensor. We have also demonstrated the integration of the sensor to a wireless network and carried out field water testing using the sensor. We envision that the field
implementation of the wireless water sensor network will enable ‘‘smart farming’’ and ‘‘smart environmental monitoring’’.