The lateral line is a critical component of fish sensory systems, found to affect numerous aspects of behavior, including maneuvering in complex fluid environments with poor visibility. This sensory organ has no analog in modern ocean vehicles, despite its utility
and ubiquity in nature, and could fill the gap left by sonar and vision systems in turbid, cluttered environments.To emulate the lateral line and characterize its object-tracking and shape recognition capabilities, a linear array of pressure sensors is used along with analytic models of
the fluid in order to determine position, shape, and size of various objects in both passive and active sensing schemes. We find that based on pressure information, tracking a moving cylinder can be effectively achieved via a particle filter. Using principal component analysis, we are also
able to reliably distinguish between cylinders of different cross section and identify the critical flow signature information that leads to the shape identification. In a second application, we employ pressure measurements on an artificial fish and an unscented Kalman filter to successfully
identify the shape of an arbitrary static cylinder.Based on the experiments, we conclude that a linear pressure sensor array for identifying small objects should have a sensor-to-sensor spacing of less than 0.03 (relative to the length of the sensing body) and resolve pressure differences
of at least 10 Pa. These criteria are used in the development of an artificial lateral line adaptable to the curved hull of an underwater vehicle, employing conductive polymer technologies to form a flexible array of small pressure sensors.
This paper presents a flexible pressure sensor array which is demonstrated to transduce underwater pressure variations produced by moving objects and surface waves. The sensors exhibit a 0.0014 fractional resistance change per 100 pascals, achieving a pressure resolution of 1.5 pascals using a 16bit analog/digital converter. Additionally, sensor operation while bent to a 0.5 m radius of curvature is demonstrated. Each sensor consists of a strain-concentrating polydimethylsiloxane (PDMS) diaphragm and a resistive strain gauge made of a conductive carbon black-PDMS composite. A one-dimensional array of 4 sensors with a 15 mm center-to-center spacing is fabricated, and the dynamic response of the sensors is characterized and modeled.
We report a novel room temperature methanol sensor comprised of gold nanoparticles covalently attached to the surface of conducting copolymer films. The copolymer films are synthesized by oxidative chemical vapor deposition (oCVD), allowing substrate-independent deposition, good polymer conductivity and stability. Two different oCVD copolymers are examined: poly(3,4-ethylenedioxythiophene-co-thiophene-3-aceticacid)[poly(EDOT-co-TAA)] and poly(3,4-ehylenedioxythiophene-co-thiophene-3-ethanol)[poly(EDOT-co-3-TE)]. Covalent attachment of gold nanoparticles to the functional groups of the oCVD films results in a hybrid system with efficient sensing response to methanol. The response of the poly(EDOT-co-TAA)/Au devices is found to be superior to that of the other copolymer, confirming the importance of the linker molecules (4-aminothiophenol) in the sensing behavior. Selectivity of the sensor to methanol over n-pentane, acetone, and toluene is demonstrated. Direct fabrication on a printed circuit board (PCB) is achieved, resulting in an improved electrical contact of the organic resistor to the metal circuitry and thus enhanced sensing properties. The simplicity and low fabrication cost of the resistive element, mild working temperature, together with its compatibility with PCB substrates pave the way for its straightforward integration into electronic devices, such as wireless sensor networks.
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