FAST TEMPORAL RESPONSE FIBER OPTIC CHEMICAL SENSORS BASED ON THE PHOTODEPOSITION OF MICROMETER-SCALE POLYMER ARRAYS

Fiber-optic chemical sensor microarrays for the detection of pH and O- 2 have been developed with subsecond response times. Sensor microarray s are fabricated by the covalent immobilization (pH sensor arrays) or the physical entrapment (O-2 sensor arrays) of fluorescent indicators in photodeposited polymer matrices on optical imaging fibers. Polymer microarrays are comprised of thousands of individual elements photodep osited as hemispheres such that each element of the sensor array is co upled directly to a discrete optical element of the imaging fiber and is not in contact with other neighboring elements. Because of the hemi spherical shape and the individuality of the array elements, diffusion of analyte to the sensor elements is dominated by radial diffusion, r esulting in a rapid response time. pH-sensitive arrays based on fluore scein respond to a 1.5-unit pH change within 300 ms, while the O-2-sen sitive arrays respond to O-2 changes within. 200 ms (90% of steady sta te response).