Indian Institute of Science

Debiprosad Roy Mahapatra

Sandeep Venkit Anand

Arvind Krishnaswamy

Devices for use in cold-field emission and methods of forming the device are generally presented. In one example, a method may include providing a conductive base, dispersing carbon-filled acrylic onto the conductive base to form a conductive film, coupling a copper plate to a first side of the conductive film, and irradiating the conductive film. The method may further include dispersing carbon nanotubes (CNTs) on a second side of the conductive film to form a substantially uniform layer of CNTs, removing excess CNTs from the second side, and curing the conductive film. In one example, a device may include a polycarbonate base, a layer of carbon-filled acrylic on one side of the polycarbonate base and a layer of irradiated carbon-filled acrylic on the other, a copper plate coupled to the carbon-filled acrylic, and a substantially uniform layer of randomly aligned CNTs dispersed on the irradiated carbon-filled acrylic.

Cold field emission cathode using carbon nanotubes

Energy harvesting elements or membranes are provided that use a layer of electrodes with a mixture of carbon nanotubes (CNT). The energy harvesting device of this type can be used as in sensor-based system in which on application of a bending load, the energy harvesting device produces a voltage across the electrodes. The energy harvesting device may include an electrode coating including carbon nanotubes (CNT) substantially homogenously dispersed in epoxy resin system to form a CNT-epoxy electrode coating. The CNT-epoxy electrode can be realized by dispersing about 5% CNT (by weight) in an epoxy-resin system, followed by mixing the system to achieve a near-homogenous dispersion resulting in a CNT-epoxy mixture. The CNT-epoxy mixture can then be uniformly coated on surfaces of a polymer to form electrodes.

Energy harvesting devices using carbon nanotube (CNT)-based electrodes

Systems and methods of harvesting and converting naturally occurring energy are described that include exposing a material to an ambient condition and harvesting at least a portion of energy that is created. Energy harvesting from fluidic and flow environments or vibration can be accomplished using types of energy harvesters, such as flexible polymers. Active materials or Electro-Active Polymer (EAP)-metal composite thin films like Ionic Polymers, Piezoceramic materials, and electromagnetic systems may be used as mechanical to electrical energy transducers. One type of an ionic EAP is ionic polymer-metal composite (IPMC), which includes a base polymer membrane that may be coated with a metal to act as a surface electrode. The surface electrode may be silver (Ag) nanoparticles. The silver nanoparticle functionalized IPMC can be used to convert mechanical vibrations and fluidic flow to electrical energy to power wireless devices and microelectronic systems, for example.

Polymer metal composite membranes

Methods and systems for sensing strain are disclosed. A thin film sensor includes a thin film polymer matrix that has two electrical terminals, conductive nanoparticles dispersed within the polymer matrix, and carbon nanotubes dispersed within the polymer matrix. The thin film sensor has a resistivity across the two electrical terminals that varies with a magnitude of strain applied to the thin film sensor. Strain may be sensed by applying a voltage to the thin film sensor, and an electrical response of the thin film sensor may be detected due to a strain present across the sensor. A magnitude of the strain can be determined based on the electrical response. Methods and systems for a memristor are also disclosed. The memristor has a resistivity that varies with a time-varying voltage input and with a time-varying strain input.

Flexible, stretchable, and distributed strain sensors

Systems and methods are provided for field emission device. An array of carbon nanotubes is arranged in a variable height distribution over a cathode substrate. An anode is provided to accelerate the emitted electrons toward an x-ray plate. Voltage is supplied across the array of carbon nanotubes to cause emission of electrons. The pointed height distribution may be linear or parabolic, and a peak height of the variable height distribution may occur in a center of the array. A side gate may also be provided adjacent the array of carbon nanotubes to provide improved electron emission and focusing control.

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Bengaluru, India

Debiprosad Roy Mahapatra