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• Carbon nanotubes (CNTs)
• CNT Mixtures/Composites Properties
• CNT based Transmission Line for Gas Sensing
• Surface Plasmon Applications
• CNT based Gas Sensing Using Surface Plasmons

• Pressure Sensor Applications
• RF Wireless Pressure Transducer Concept
• RF Wireless Pressure Transducer
• RF Pressure Transducer
• Simulation Results at 30 – 55 GHz
• Prototype for Implementation at 5-8 GHz Range
• Measured Results at 5-8 GHz Range
• Conclusions

• Polarized Nano-material (PNM)
• Characterization set up
• S-parameter Measurements
• Impedance Analysis

• Properties and Applications

Electromagntic Applications in Nanotechnology

Team:
Gerald DeJean, Daniela Staiculescu, Trang Thai, Justin Ratner, Li Yang

Carbon nanotubes (CNTs)

• Hexagonal networks of carbon atoms
  • 1nm in diameter
  • 1 to 100 microns of length
• Layer of graphite rolled up into a cylinder
• Manufactured:
  • Carbon arc-discharge technique
  • Laser-ablation technique
  • Chemical vapor decomposition technique (CVD)
• Dielectric proces controlled through:
  • Tube diameter
  • Chirality
  • Doping

• Single Wall Nanotube – 1 Wall
• Double Wall Nanotube – 2 Walls
• Multi-Wall Nanotube ~ 50 Walls

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CNT Mixtures/Composites Properties

• Different mixtures of CNTs (Ceramic/SWNT, Epoxy/SWNT, Epoxy/MWNT, etc.)
      => conductivity ranging from 10-3 to 102
• Control weight % of CNTs in the composites
      => dielectric constant in the range of 1-16 around 1-20GHz range
• Adsorption of different gases cause different changes in:
  • Dielectric constant
  • Loss tangent
• Funtionalized CNTs in composites to improve gas sensitivity
• Vertically allignment of CNTs in composites to improve gas sensitivity
• Quick response time (smaller than contemporary sensors)
• Ultra-high sensitivty (order of part-per-billion and part-per-million)
• System is reversible, however long recovery time

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CNT based Transmission Line for Gas Sensing

• The substrate is a CNT based materials that are sensitive to gases such as NOx, Nitrogen, Carbon dioxide, etc.
• When in contact with intruding gases, the dielectric constant and conductivity of the CNT material are altered.
• A co-planar transmission line with CNT based substrate was known to produce magnitude and phase changes in the transmitted signal when in contact with the intruding gases.
• The CNT transmission line is utilized with our designed antenna and system in Figure 1 to produce observable parameters for easy detection in wireless gas sensing.

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Surface Plasmon Applications

• Using Surface Plasmon Resonance (SPR) to detect changes in electrical properties of CNT based material thin films
• Grating structure to couple waves in microwave range frequencies
      => integrating with standard wireless network
• The shift in frequency (hundred of MHz in the operating range of 60 GHz) and changes in magnitude of the reflected waves allows accurate remote gas sensing.
• Our designed sensor is completely passive and capable of selective sensing.

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CNT based Gas Sensing Using Surface Plasmons

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A Novel Front-End Radio Frequency Pressure Transducer Based on a Dual-band Resonator for Wireless Sensing

Team:
Trang Thai, Gerald DeJean

Pressure Sensor Applications

• Automation: measuring full/empty tank os liquid, leakage monitoring, etc.
• Process control
• Electronics: microphones
• Automotive: engine condition, airbag, acceleration monitoring, tire pressure, etc.
• Medical: blood, artery, intracranial pressure monitoring, hearing aid equipments, etc.
• Public safety: weather, food processing, use together with gas sensors

RF Wireless Pressure Transducer Concept

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RF Wireless Pressure Transducer

• Fewer components
• Smaller system size
• Less power consumption

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RF Pressure Transducer

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Simulation Results at 30 – 55 GHz

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Prototype for Implementation at 5-8 GHz Range

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Measured Results at 5-8 GHz Range

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Conclusions

• A new highly sensitive radio frequency pressure transducer at millimeter wave frequency range
• Seamlessly integrated with other RF circuits in the LTCC multilayer packaging technology
• Dualband between 30-55 GHz:
  • A wireless communications link
  • A remote sensing differential pressure indicator
• Simplify the design process, reduce the device’s size, and reduce power consumption of the sensor at device level
• Providing a sensitivity of 116 MHz/um
• Proof-of-concept prototype at 5-8 GHz: sensitivity 250 MHz/787um
• Future work:
  • The millimeter wave prototype based on LTCC using Si membrane
  • Modifications for multilayer organics, such as LCP that allow realization of wireless implantable sensors for biomedical applications

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Characterization and Testing of Novel Polarized Nanomaterial Textiles for Ultrasensitive Wireless Gas Sensor

Team:
Trang Thai, Justin Ratner, Gerald DeJean

Collaborator:
Wenhua Chen (State Key Lab on Microwave & Digital Communication, Tsinghua University, Beijing, China)

Polarized Nano-material (PNM)

• Carbon nanotubes (CNTs) are grown on a Silicon substrate into super-aligned nanotube arrays
• PNM samples are formed by continuous yarns of pure CNT bundles aligned parallel to one another due to van der Waals interations
• Highly polarized and excellent shielding effect
• Investigated at Ka-band (26.5 – 40 GHz) for millimeter wave applications such as ultrasensitive gas sensing

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Characterization set up

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S-parameter Measurements

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Impedance Analysis

• The impedance profiles of polarizations 1 and 3 show the distinct resonance characteristics of radiators
• The first time the collective resonance behavior of the carbon nanotubes is shown in the microwave range due to highly aligned CNTs in the PNM layers

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Study of Graphene Nanoribbons in Microwave frequency range

Team:
Trang Thai, Gerald DeJean

Collaborator:
Dr. DeHeer’s Expitaxial Graphene Lab (School of Physics, Georgia Institute of Technology)

Properties and Applications

• Extraordinary electrical and mechanical properties similar to carbon nanotubes
• Capable of being patterned into desired geometry
• High carrier mobility => ideal material for detecting THz radiation
• Passive components such as antennas and interconnects (transmission lines) => enable complete integrated graphene based electronics
• We investigate the planar epitaxial graphene structures grown on SiC substrates:
  • Conductance and scattering parameter study of GNRs in 2-port network at millimeter and sub-millimeter wave signals
  • Gas sensing capability of GNRs for highly sensitive wireless sensors

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