Description and Characterisation of a Large Array of Sensors Mimicking an Artifical Olfactory Epithelium

Biological olfactory systems show high sensitivity and exquisite discriminatory capacity to odorants. These characteristics are due to hierarchical signal processing of the large numbers of sensory inputs that occurs within the olfactory system. In testing realistic computational models of the olfactory system, large numbers of chemical sensor inputs are required. So far, sensory devices that may serve as model inputs to an artificial olfactory system do not exist. The development of a large scale array of chemical sensors able to mimic the olfactory receptor neurons is described, and these have been characterised in terms of their variability and degree of redundancy. Using this device it is possible to start testing computational hypotheses appropriate to biological chemosensory systems and adapt them to the artificial olfaction

An investigation into spike-based neuromorphic approaches for artificial olfactory systems

The implementation of neuromorphic methods has delivered promising results for vision and auditory sensors. These methods focus on mimicking the neuro-biological architecture to generate and process spike-based information with minimal power consumption. With increasing interest in developing low-power and robust chemical sensors, the application of neuromorphic engineering concepts for electronic noses has provided an impetus for research focusing on improving these instruments. While conventional e-noses apply computationally expensive and power-consuming data-processing strategies, neuromorphic olfactory sensors implement the biological olfaction principles found in humans and insects to simplify the handling of multivariate sensory data by generating and processing spike-based information. Over the last decade, research on neuromorphic olfaction has established the capability of these sensors to tackle problems that plague the current e-nose implementations such as drift, response time, portability, power consumption and size. This article brings together the key contributions in neuromorphic olfaction and identifies future research directions to develop near-real-time olfactory sensors that can be implemented for a range of applications such as biosecurity and environmental monitoring. Furthermore, we aim to expose the computational parallels between neuromorphic olfaction and gustation for future research focusing on the correlation of these senses

Sensor-based machine olfaction with neuromorphic models of the olfactory system

Electronic noses combine an array of cross-selective gas sensors with a pattern recognition engine to identify odors. Pattern recognition of multivariate gas sensor response is usually performed using existing statistical and chemometric techniques. An alternative solution involves developing novel algorithms inspired by information processing in the biological olfactory system. The objective of this dissertation is to develop a neuromorphic architecture for pattern recognition for a chemosensor array inspired by key signal processing mechanisms in the olfactory system. Our approach can be summarized as follows. First, a high-dimensional odor signal is generated from a chemical sensor array. Three approaches have been proposed to generate this combinatorial and high dimensional odor signal: temperature-modulation of a metal-oxide chemoresistor, a large population of optical microbead sensors, and infrared spectroscopy. The resulting high-dimensional odor signals are subject to dimensionality reduction using a self-organizing model of chemotopic convergence. This convergence transforms the initial combinatorial high-dimensional code into an organized spatial pattern (i.e., an odor image), which decouples odor identity from intensity. Two lateral inhibitory circuits subsequently process the highly overlapping odor images obtained after convergence. The first shunting lateral inhibition circuits perform gain control enabling identification of the odorant across a wide range of concentration. This shunting lateral inhibition is followed by an additive lateral inhibition circuit with center-surround connections. These circuits improve contrast between odor images leading to more sparse and orthogonal patterns than the one available at the input. The sharpened odor image is stored in a neurodynamic model of a cortex. Finally, anti-Hebbian/ Hebbian inhibitory feedback from the cortical circuits to the contrast enhancement circuits performs mixture segmentation and weaker odor/background suppression, respectively. We validate the models using experimental datasets and show our results are consistent with recent neurobiological findings

Implementación de un sistema de evaluación sensorial electrónico para el control de calidad de vinos

Esta investigación está dedicada fundamentalmente a la aplicación de nuevos métodos de análisis de datos para mejorar los resultados obtenidos por los sistemas de valoración sensorial electrónica. Los métodos desarrollados entregaron soluciones fiables, robustas, y lo más importante adecuadas y adaptadas concretamente a la necesidad específica del problema de partida. Una parte fundamental del trabajo ha sido la modificación, estimación e integración de diferentes algoritmos de procesado de señales. Entre ellos se han aplicado algoritmos multivariantes como el PCA (Análisis de componentes principales), PLS (Regresión por mínimos cuadrados parciales), y métodos quimiométricos avanzados como el Tucker3, el ANOVA-PLS y el PLS-GA. De esta manera se ha evaluado y demostrado el potencial que tienen la nariz y lengua electrónica diseñadas en nuestro grupo de investigación para el control de calidad y caracterización organoléptica de vinos. Con estos dispositivos electrónicos y nuestros tratamientos quimiométricos ha sido posible llegar a un conocimiento más profundo de los fenómenos que tienen lugar en diversas situaciones vinculadas a la aplicación de nuevas tecnologías en la elaboración del vino, como son el uso de métodos alternativos para su envejecimiento, el uso del tapón sintético para su embotellado y el efecto de la fermentación barrica de roble en los vinos blancos.Departamento de Física de la Materia Condensada, Cristalografía y Mineralogí