Caso de Estudio 3: Participación de los televidentes en los servicios interactivos propuestos

7.1

Summary of contributions

This dissertation describes a body of work conducted to develop a smart, label- free cell-based chemoreceiver for artificial insect olfaction. The central challenge of the thesis was to mimic nature in both cellular and molecular levels on to a technological platform which aids in the development of a new class of technology for infochemical communication. A surface acoustic wave based microsensor has been used to develop functional technological equivalents of the cellular and molecular mechanisms that mimics the pathway between pheromone production and detection in insects. The concept of chemical info communication has been initially explored with the aid of polymer-based gas-phase measurements, which imitates the molecular machinery of chemical olfaction. This was followed by the investigation of the feasibility of using the prototype cell-based biosensor system in a static mode for artificial insect olfaction mimicking the cellular detection in the receptor/antenna apparatus of insects. Finally, as part of the development of a compact and low-power portable chemoreceiver system, the sensor drive and interface circuitry was deployed in an analogue VLSI chip, thereby overcoming the associated measurement complexity and equipment cost.

The work carried out in this thesis has made several original contributions to the development of a smart, low-cost, portable and label-free acoustic resonator based chemoreceiver, which are summarized below:

 An info-chemical communication system has been developed, which employs uniquely ratiometrically encoded chemical signals. The system consists of a chemoemitter module, which is capable of releasing a predefined ratio of

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volatile compounds utilizing an artificial gland. An array of polymer-coated piezoelectric SAWR sensors forms the chemoreceiver module, which helped in the detection of vapor-phase chemical blends released into the environment.

 The encoding, transmission, and decoding of ratiometric information based upon volatile based binary mixtures of info chemicals firstly using fruit volatiles and later with insect pheromones has been demonstrated through the recovery of blend ratios by obtaining a classification of chemical ratios. Ratiometric information has been successfully recovered based on both the stationary and the transient sensor responses. Small scale, high-throughput infochemical communication has been made possible by a combination of precise spatiotemporal signal generation using plant volatiles and sex pheromones with highly sensitive detection and signal processing.

 A dual surface acoustic wave based whole cell sensor system has been developed, utilizing transfected odorant receptors, with the aid of an automated microfluidic ligand delivery system. This resulted in the development of a SH- SAW sensor functionalized with specific insect ORs (such as Or22a and Or67d) that are introduced into Sf9 cells, which allowed the acousto-electric detection of the binding of associated ligands.

 Successfully deposited and attached live Sf9 cells on to the SAWR sensors, which formed a functionalized biolayer for specific ligand detection and also detected the change in intra-cellular calcium levels when the ligand binds to the receptors. The cell adherence and growth pattern witnessed in SAW resonators proves the aptness of Sf9 cells for use as a biological functional layer on MEMS based acoustic resonators.

 An ASIC chip has been developed for the integration of the olfactory sensor drive, control and interface circuitry, as part of the development of a compact and low-power portable chemoreceiver system. This AVLSI chip has been developed using the standard CMOS 0.35 µm process which has the ability to allow the monolithic integration of CMOS circuitry with acoustic MEMS sensors.

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7.2

Future Work

The work presented in this thesis has opened up the opportunity for the work to be extended in other future projects. Other prospective projects that may arise from this work are listed below:

7.2.1 Ultrafine Particle Sensing

This thesis has paved the way for the development of a particle sensor based on acoustic sensors such as SAWs and FBARs as they can be used for mass-sensing applications. As part of this development, miniaturised particle sensors have been designed and developed utilizing SAW sensors and SMR devices for the detection of particulate matter (PM2.5 and PM10). This resulted in the development of a particle

sensor SiP, capable of performing air quality monitoring. Further work is being carried out towards the development of a CMOS monolithic low-cost and low-power miniaturised particle sensor based on FBAR technology, for the real-time monitoring of particulate matter.

7.2.2 Liquid phase detection with different cell types

In conclusion, there is an opportunity to investigate the use of immobilised receptors on the acoustic sensor surface, possibly based upon locusts that have been shown to survive in dry conditions and so may be used for airborne molecular detection. Additionally, other forms of acoustic wave micro sensors such as FBAR devices could be explored instead of SAW sensors in order to design the cell-based chemoreceiver to be used in artificial olfaction. Thus the polymer coated SAWR sensor array can be substituted by a polymer FBAR array for improved sensitivity. This could allow the exploration of immobilised proteins on the surface of the FBAR sensors resulting in the development of a BioMEMS chip to create an artificial biosensing unit. The use of FBAR devices improves the sensitivity of the sensors due to their higher frequency of operation. Due to their compact size and CMOS compatibility, it is possible to develop a monolithic FBAR-CMOS based BioMEMS