A compact, LED-based phase fluorimeter-detection system for chemical and biosensor arrays

This paper describes a design for an inexpensive phase fluorimeter based on blue or green light emitting diodes (LEDs) for use with chemical and biological sensors with fluorescence and phosphorescence lifetime-based transduction. The phase fluorimeter is based on a personal computer, two frequency synthesizers and off-the-shelf optical and electronic components and has an estimated lifetime resolution better than 10 ps. The phase fluorimeter is especially well-suited for implementation with arrays of chemically-sensitive (e.g., bioreceptive) elements. The data acquisition system allows rapid monitoring of light emission from fluors or phosphors immobilized in the chemically sensitive array elements, each of which can be designed to be responsive to a particular chemical analyte. This paper descibes chemically-sensitive elements based on ultrathin films of porous polymers (e.g., formed by sol-gel processing) and on self-assembled monolayers (SAMs). The paper focuses on methods for detection of low levels of luminescence emission from micropatterned array elements that comprise sensor arrays. Of particular importance is the detection of low levels of fluorescence and phosphorescence from SAMs of alkanethiolates on thin gold and silver films. Methods for enhancing the luminescence yield from these SAMs include optimization of the dielectric environment of the luminescent dyes and surface plasmon resonance (SPR) enhanced excitation.