|
Porous silicon (PSi) is a particularly attractive material for biological and high-tech applications because of the ease with which the optical properties, pore size, and surface chemistry can be manipulated. The position, width and intensity of spectral reflectivity peaks are controlled by current density, waveform and solution composition used in the electrochemical etch. This allows the preparation of PSi photonic crystals that can display any number of colors within the visible spectrum with high color saturation and resolution, highly desirable features for information display. Researchers at the University of California, San Diego, have converted these films into micron-sized particles (so-called “Smart Dust”, described in: Link and Sailor, Smart Dust: Self-assembling, self-orienting photonic crystals of porous Si.; Proc. Nat. Acad. Sci., 2003, 100 (19): p.10607-10610).
Recently, University researchers have demonstrated magnetically switchable micron-sized photonic crystals that can be induced to flip between a colored photonic crystal face and a black, non-reflective surface in an oscillating magnetic field, at rates exceeding 175 Hz. This property makes this an excellent material for use in display applications.
In addition, magnetic Smart Dust has now been constructed with amphiphilic properties. This allows the micron-size crystals to self-align at the interface between immiscible liquids and effectively encapsulate suspended droplets. The addition of the magnetic property means that the particles can be used to manipulate microliter-scale droplets or cells by the application of an electromagnetic field, without the addition of ions or other impurities to the bulk liquid. Possible application areas include MEMS devices, microfluidic mixing, targeted drug/enzyme delivery, biological screening, and microfluidic tagging.
References: Summary of Professor Michael Sailor's porous silicon-based technology platform; June 2005.
This technology is presently available for licensing.
Case Nos: SD2004-206 and SD2004-270
LabLink: http://chem-faculty.ucsd.edu/sailor/research/
Inquiries To: invent@ucsd.edu
|
