Daniel Filippini

Bringing Chromatography Back To Colour

Biological systems enhance the odor discrimination capabilities by performing a small separation of complex mixtures. This principle may be successfully exploited in the development of new sensor platforms. The aim of the presented work is to implement the gas‐chromatographic separation principle for chemical sensing. Herein we report a simple way of imaging gas diffusion through a channel by means of optical changes occurring in a track that contains a chemical indicator embedded in a polymeric matrix.

Chemical Sensitivity of Functionalized Cotton Yarns

The concept of integration of sensors into textiles emerged in recent years mostly considering physical sensors, however a large number of applications of chemically sensitive fabrics can be easily devised. Optical detection offers simple and ready methodologies for the development of such sensor systems. Here, we report an array of cotton yarns functionalized with different colorimetric indicators sensitive to different volatile compounds. Results indicate that indicators in cotton preserve their sensitivity and that colorimetric measurement using computers peripheral devices can be used for analytical purposes.

The Role of Spike Temporal Latencies in Artificial Olfaction

In this paper we investigate the recognition power of spike time latencies in an artificial olfactory system. For the scope we used a recently introduced platform for artificial olfaction implementing an artificial olfactory epithelium, formed by thousands sensors, and an abstract olfactory bulb1. Results show that correct volatile compounds classification can be achieved considering only the first two spikes of the neural network output evidencing that the latency of the first spikes contains actually enough information for odor identification.

Testing olfactory models with an artificial experimental platform

Artificial olfaction systems have been investigated since more than two decades on alleged property of similarities between the receptive field of natural receptors and artificial sensors. Due to the limited number of sensors embedded in these systems the complexity of electronic noses is generally too low to allow the application of olfaction processing models. Actually the literature there are several models attempting to describe some olfaction functionalities, and the availability of an artificial platform to test models could be of great benefit for these studies. Recently, the use of optical image sensors has been demonstrated as a simple method to obtain large sensor arrays. Furthermore, an elegant and simple method to cluster individual sensors in classes allows for the definition of epithelium and glomerular layers. This system enables the application of a complex olfaction model, and these properties are here illustrated applying a glomerular compartmentalization model to the data generated by the exposure of such an artificial system to pure and mixed gases.

Multiparametric light-assisted silicon device transduction of molecular recognition events

The contemporaneous measurement of different physical properties of a chemical sensing layer is expected to provide a general increase of selectivity. The application of this concept generally requires the use of multiple devices. In this paper, the measurement of optical and electric properties of one sensing layer with a single device is presented. The surface potential and optical sensitivities of a field effect transistor are utilized to develop a multi-parametric sensor able to evaluate, at the same time, changes in the electric dipole and in the optical absorbance of a metalloporphyrin layer. The properties of the multiparametric approach are illustrated with an example aimed at recognizing different gases and vapours.

An Artificial Olfaction System Formed by a Massive Sensors Array Dispersed in a Diffusion Media and an Automatically Formed Glomeruli Layer

Optical imaging is a read‐out technique for sensors that can easily provide advances in artificial olfaction implementing features such as the large number of receptors and the glomeruli layer. In this paper an artificial olfaction system based on the imaging of a continuous layer of chemical indicators is illustrated. The system results in an array of thousands of sensors, corresponding to the pixels of the image. The choice of Computer Screen Photoassisted Technology as a platform for optical interrogation of the sensing layer allows for the definition of a strategy for an automatic definition of the glomeruli layer based on the classification of the optical fingerprints of the image pixels. Chemical indicators are dissolved into a polymeric matrix mimicking the functions of the olfactory mucosa. The system is here illustrated with a simple experiment. Data are treated applying a lateral inhibition to the glomeruli layer resulting in a dynamic pattern resembling that observed in natural olfaction.

Optical transduction of the chemical sensitivity of porphyrin nanotubes by CSPT platform

Nanostructured molecular assembly provides, in many cases, peculiar properties that are not found in the individual constituents. Among three-dimensional arrangements the tubular structures are particularly appealing for chemical sensor applications for expected surface increase and cavity effects. In this paper, the sensing properties of self-assembled nanotubes of oppositely charged porphyrins are investigated by measuring the changes of their optical properties. Computer screen photoassisted technology (CSPT) is utilized as a simple and practice platform to test the optical sensitivity of sensing materials and to develop chemical sensing systems.