C. Cunniffe

A review of digital data acquisition hardware and software for a portable electronic nose

This paper discusses the digital hardware and software that is required for data acquisition in a portable electronic nose (e‐nose) system. A review of current e‐nose systems is presented highlighting the methods employed by these systems to acquire the data from the sensor head.

Custom electronic nose with potential homeland security applications

Detailed in this work is the design and development of a handheld electronic nose nose with an array of conducting polymer composite film sensors interfaced to a Compaq iPAQ. The device has potential applications in homeland security, such as screening people packages, luggage and vehicles at key locations such as airports or government buildings, for the prevention of terrorist attacks. The overall system design consisted of a Compaq iPAQ used for the main computing and controlling of the device, connected to the custom built electronic nose interface. The electronic nose interface was designed to fit into the iPAQ expansion case providing a fully integrated system. An array of eight conducting polymer composites were inserted into the modular sensing head for the detection of organic solvents.

Drop-Coated Polyaniline Composite Conductimetric pH Sensors

This work describes the fabrication and development of a polyaniline based conductimetric pH sensor. Two types of drop coated polyaniline films were investigated and it was found that the undoped emeraldine base polyaniline produces the best electrical response to pH. The results obtained show that the lowest conductance of these films occurs at the lowest pH value (pH2), with the conductance increasing with increasing pH. It is thought that this response is due to effects from the polymer binder, which is used to increase adhesion between the pH-sensitive film and the substrate.

A novel approach to electronic nose-head design, using a copper thin film electrode patterning technique

Presented in this paper is a process for manufacturing copper electrode patterns on alumina substrates using thin film deposition, spin coating and printed circuit board (PCB) etching techniques. The process was used for the design and manufacture of an array of gas sensors for use in an electronic nose system. This approach was executed in three phases. Firstly a 500nm layer of copper was deposited onto the alumina substrate. Secondly photoresist was applied by spin coating onto the copper layer and finally the PCB etching process was used to achieve the final electrode pattern. Conducting polymer composite materials were deposited onto the resulting electrode patterns producing an array of sensors for vapour detection. The sensor array showed good responses to Propanol at concentrations ranging from 5000ppm to 30000ppm with fast recovery times. The sensor array was slotted into an electronic nose system and an illustrative analysis of the sensor arrays ability to discriminate between different solvents was carried out with promising results

NiO-TiO/sub 2/ thick-films for detection of alcohol vapours at room temperature

The response of screen-printed thick-films of NiO/TiO/sub 2/ to organic solvent vapours was studied. It was found that these films displayed a significant resistance change in response to the vapours even at room temperature. The sensors displayed an inherent selectivity, proving most sensitive to toluene and propanol vapour; with comparatively low responses exhibited towards ethanol and methanol vapours. Very fast response and recovery times of 9 s and 16 s respectively were recorded for the devices upon exposure to 4000 ppm step changes in propanol concentration.

Surfactant treated drop-coated polyethylene adipate \ carbon black nanocomposite sensor for alcohol vapour detection

� Abstract— This paper describes the effect of hypermer PS3 surfactant on the response of PEA \ CB sensors to 20000 ppm of propanol. The surfactant was varied from 10-50 mg and its effect on the response and properties of the sensor material were examined. It was found that increasing the amount of surfactant in the sensors significantly improved batch-to-batch reproducibility in addition to the sensitivity of each device. This is due to a more homogenous dispersion of the carbon black (CB) filler particles achieved by the addition of surfactant. It is concluded that this approach can be used to optimize the sensitivity and reproducibility of conducting polymer composite (CPC) sensor devices. Keywords—Conducting polymer composites, surfactant, drop coating, alcohol vapour detection

Anomalous Behavior of Carbon Filled Polymer Composites Based Chemical and Biological Sensors

This paper details results obtained from an array of drop coated room temperature carbon filled polymer composite sensors showing anomalies in the initial responses of the devices. The paper details the construction of the sensors, and the theory of their operation. The manufacture techniques are introduced along with the experimental configuration used to acquire the results.

Response of poly(vinyl acetate)/carbon black composites to ethanol vapour and temperature

The effect of ethanol vapour and temperature was investigated on gas sensors fabricated from poly(vinyl acetate)/carbon black composites based around a predetermined percolation threshold. Samples with 8% carbon black loading displayed the best response to the ethanol vapour. Typical response and recovery times of 140s and 45s respectively were recorded. In addition, bridge structures were fabricated, where all four resistive elements were prepared from the same composite material and in which a novel passivation process was employed. It was observed that these bridge structures were significantly less affected by variations in temperature in comparison to the single sensor structures.

Nanopatterning Using the Bioforce Nanoenabler

This paper discusses the opportunities, offered by novel nanopatterning facilities, namely, BioForce NanoeNabler™ (NeN), in the area of sensors development, with the focus on microsensor arrays for biological, environmental and medical fields. The NeN can deliver attolitre to picolitre volumes of liquid, such as small molecules, biomolecules, including proteins and nucleic acids, nanoparticles, reactive solutions and so forth, with a high degree of spatial accuracy. It is envisaged that the reduction in the sensors size would result in their new advanced functionalities.

Detection of Ralstonia Pickettii Bacteria in M9 Medium using Polymer Nanocomposite Sensors

Detection of bacteria such as Ralstonia pickettii in high purity water (HPW) has gained increasing interest for researchers. Contamination problems in HPW in both pharmaceutical and semiconductor applications can lead to a reduction in performance and inefficiency in production chains leading to huge expense. Real time detection of these bacteria in HPW prior to use can allow corrective action to be taken sooner, by reallocating the water for repurification or utilization elsewhere thereby reducing industrial costs The aim of this study was to evaluate the responses of polymer nanocomposite sensors to increasing concentrations of Ralstonia pickettii bacteria. M9 minimal growth medium was used to grow the bacteria and three different concentrations were prepared by taking samples after 2 hours, 4 hours and 6 hours of growth. The sensors showed large sensitivity to each concentration of bacteria and produced a decrease in response over the growth cycle of the bacteria. These sensors demonstrated the ability to detect early stage actively growing cells in real time, which is of large benefit to HPW applications. This work has shown that these sensors can be used to detect both lag phase and late exponential and stationary phase growing cells in a minimal nutrient environment.