Sterling E. McBride

A machine-vision system for iris recognition

This paper describes a prototype system for personnel verification based on automated iris recognition. The motivation for this endevour stems from the observation that the human iris provides a particularly interesting structure on which to base a technology for noninvasive biometric measurement. In particular, it is known in the biomedical community that irises are as distinct as fingerprints or patterns of retinal blood vessels. Further, since the iris is an overt body, its appearance is amenable to remote examination with the aid of a machine-vision system. The body of this paper details the design and operation of such a system. Also presented are the results of an empirical study in which the system exhibits flawless performance in the evaluation of 520 iris images.

A system for automated iris recognition

This paper describes a prototype system for personnel verification based on automated iris recognition. The motivation for this endeavour stems from the observation that the human iris provides a particularly interesting structure on which to base a technology for noninvasive biometric measurement. In particular, it is known in the biomedical community that irises are as distinct as fingerprints or patterns of retinal blood vessels. Further, since the iris is an overt body its appearance is amenable to remote examination with the aid of a computer vision system. The body of this paper details the design and operation of such a system. Also presented are the results of an empirical study where the system exhibits flawless performance in the evaluation of 520 iris images.<<ETX>>

Electrohydrodynamic Pumps for High-Density Microfluidic Arrays

We have developed electrohydrodynamic (EHD) pumps for fluid delivery in high-density microfluidic arrays as part of a drug discovery collaboration with Orchid Biocomputer, Inc. and SmithKline Beecham Pharmaceuticals. The multi-layer array structures are fabricated in glass and silicon, and have no moving parts. Each pump is comprised of two planar-processed, conductive via electrodes that are in contact with fluid inside the array. Typical applied voltages (300–500 V) result in pressures on the order of inches of water. EHD pumping in microfluidic array chips has been demonstrated and characterized for flow direction and relative pumping efficiency with more than one hundred different organic solvents and solvent-reagent compounds. A basic theory for the phenomena is presented, and quantitative velocity measurements for some representative solvents are shown.

Dispersion engineering of photonic crystals

In this paper we discuss the design and implementation of integrated planar optical devices realized by exploiting the unique dispersion properties of photonic crystal (PhC) devices. In particular, we demonstrate the ability to focus and spatially route optical beams in the absence of channelized structures. By this we mean that these devices do not contain any form of lateral confinement, in the sense of a physical structure, other than the dispersion properties of the crystal lattice. To this end, lateral control is imposed on the propagating wave by virtue of engineering the band structure of the photonic crystal lattice. Our approach to this effort is based on engineering the dispersion diagram of a given periodic structure outside of its band gap. As such, this allows for the determination of unique propagation characteristics and corresponding devices, as we show in theoretical simulations and experimental results.

Modulating dispersion properties of low index photonic crystal structures using microfluidics

We present a technique for manipulating the dispersive properties of low index periodic structures using microfluidic materials that fill the lattice with various fluids of different refractive indices. In order to quantify the modulation of the optical properties of the periodic structure we use Equifrequency contours (EFC) data to calculate the frequency dependant refractive index and the refractive angle. We further introduce various types of defects by selectively filling specific lattice sites and measuring the relative change in the index of refraction. Finally we design and optically characterize an adaptive low index photonic crystal based lens with tunable optical properties using various microfluidics. We also present experimental results for a silicon based PhC lens used an optical coupling element.

Configurable photonic crystal based devices and applications

We present a technique for manipulating the dispersive properties of low index periodic structures using microfluidic materials that fill the lattice with various fluids of different refractive indices. In order to quantify the modulation of the optical properties of the periodic structure we use Equi-frequency contours (EFC) data to calculate the frequency dependant refractive index and the refractive angle. We further introduce various types of defects by selectively filling specific lattice sites and measuring the relative change in the index of refraction. Finally we design and optically characterize an adaptive low index photonic crystal based lens with tunable optical properties using various microfluidics. We also present experimental results for a silicon based PhC lens used an optical coupling element.