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Chemical & Biomolecular Engineering

Projects


1. Device piggybacked on bacteria

Device PiggybackElectronics on Bacterium: A Bacteria/nanoparticle hybrid device is operated by applying a bias of 10V across the bacterial bridge and measuring the device current. Typical current as a function of relative humidity for "up" (i.e., humidity decreasing) and "down" cycles shows no hysteresis. The increase in current for humidity change from 20% to 2% is 40-fold (after background subtraction). The inset shows two typical bacterial bridges spanning between the electrodes. Source: Angewandte Chemie, 2005, 44, 6668.
Download: Bacteria Device (.pdf)

2. Electronic Skin

Electronic SkinHigh resolution tactile sensor: A 100 nm thick electro-optical nanodevice is designed to convert pressure into light. When a U.S. one cent coin is pressed against the 100 nm thick nanodevice, the embossing produces a pressure distribution which is directly imaged on a CCD camera. The "stress" image corresponds well with President Lincoln's profile embossed on the coin. The spatial resolution and stress sensitivity of the device is comparable to the sensitivity of the human finger. The resolution is 10-fold better than current technology.
Source: Science, 2006, 312, 1501-1504;
Read Article: High-Resolution Thin-Film Device to Sense Texture by Touch

3. Au coated DNA

AU coated DNAAu nanowire on DNA: A 20 nm thick continuous coating on immobilized DNA spanning between electrodes 50 micron apart is achieved by a photochemical process. The resultant wire is electrically conducting with ohmic behavior indicating excellent electrical contact between the wire and the electrodes.

4. "Welding" chains of nanoparticles

Welding NanoparticlesAu nanowire on DNA: A 20 nm thick continuous coating on immobilized DNA spanning between electrodes 50 micron apart is achieved by a photochemical process. The resultant wire is electrically conducting with ohmic behavior indicating excellent electrical contact between the wire and the electrodes.

5. The nanosink

NanosinkSinking in Nano-film: Atomic Force Microscope (AFM) images of block copolymer at various stages of aging: (a) The as-cast film shows a "finger-print" pattern where the lines are polystyrene cylinders of diameter ~15 nm. (b) After 314 hours of aging at room temperature the cylinders disappear. (c) On removing ~4 nm of surface layer by reactive ion etch plasma the cylinder reappear indicating the cylinder were gradually sinking in the ~60 nm thick film. The estimated rate of sinking is ~0.16nm/day. The AFM images are 2x2 microns.
Source: Applied Physics Letters, 2002, 80, 4425.

Download:
Applied Physics Letters (.pdf)
Macromolecules (.pdf)

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