Convergent, Self-Encoded Bead Sensor Arrays in the Design of an Artificial Nose

Abstract

We report a new approach to designing an artificial nose based on high-density optical arrays that directly incorporate a number of structural and operational features of the olfactory system. The arrays are comprised of thousands of microsphere (bead) sensors, each belonging to a discrete class, randomly dispersed across the face of an etched optical imaging fiber. Beads are recognized and classified after array assembly by their unique, "self-encoded" response pattern to a selected vapor pulse. The high degree of redundancy built into the array parallels that found in nature and affords new opportunities for chemical-sensor signal amplification. Since each bead is independently addressable through its own light channel, it is possible to combine responses from same-type beads randomly distributed throughout the array in a manner reminiscent of the sensory-neuron convergence observed in the mammalian olfactory system. Signal-to-noise improvements of approximately n1/2 have been achieved using this method.

Neuromorphic Processing for Optical Microbead Arrays: Dimensionality Reduction and Contrast Enhancement

“…The microbead array technology used in this research was originally developed by Walt and colleagues at Tufts University [4], [5]. Typically, each array includes thousands of bead sensors that are made from various materials (e.g., Si or PMMA) that can be porous in order to increase surface areas.…”

“…In contrast, olfactory systems rely on a large number of receptor types ( 1000 receptors in humans [3]), and each receptor type is massively replicated. To narrow the dimensionality gap between biological olfactory systems and their current artificial counterparts, we propose a chemical sensing approach based on optical microbead technology [4], [5]. Each microbead is a cross-selective sensor, and thousands of microbeads can be assembled into a single fiber-optic bundle.…”

Microsystems for optical gas sensing incorporating the solvatochromic dye Nile Red

“…The field of artificial olfaction and gas determination is one of the fastest growing areas of sensing both commercially and within academic research areas [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Much of the work in this field to date concentrates on identification and quantification of multiple analyte species by employing miniaturised sensors.…”

“…Electronic nose systems have been produced using a variety of different sensor types, including surface acoustic wave devices, [1][2][3] conducting polymers, [4][5][6] metal oxide semiconductors, [7] carbon black/polymer composite gas sensors, [8][9][10] and fluorescent microspheres [11][12][13]. In the work presented here, we have chosen to explore the area of 3 optical sensor arrays based upon the use of solvatochromic dyes.…”

Superficies químicamente modificadas para la detección colorimétrica y eliminación de aniones de interés medioambiental en aguas

“…Si se compara con otros materiales inorgánicos para la detección de VOCs como las zeolitas, 85 el material híbrido presenta la ventaja de poseer mayores diámetros de poro, permitiendo mayores velocidades de difusión, y mejor adaptación a la superficie. Esta aproximación híbrida también muestra ventajas sobre polímeros sensores 86,87 debido a la fácil funcionalización covalente en soportes inorgánicos, el elevado orden en las estructuras 3D y que permiten evitar problemas por hinchamiento.…”