Dielectric measurements of nanoliter liquids with a photonic crystal resonator at terahertz frequencies

Journal Article · Mon Jul 20 00:00:00 EDT 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4927242· OSTI ID:22486349

Watts, C.; Klein, N. ^[1]; Otter, W. J.; Lucyszyn, S. ^[2]

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1. Department of Materials, Imperial College London, SW7 2AZ London (United Kingdom)
2. Centre for Terahertz Science and Engineering, Imperial College London, SW7 2AZ London (United Kingdom)

We present a highly sensitive technique for determining the complex permittivity of nanoliter liquid samples in the terahertz band based on a photonic crystal resonator and microcapillary. Liquids are characterized by using a capillary tube to introduce a ∼4 nl liquid sample into the electromagnetic field of a resonant mode confined by an L3 resonant cavity in a high-resistivity silicon photonic crystal slab. Monitoring the perturbation of the resonant frequency and unloaded Q-factor of the resonant mode at 100 GHz and ∼5800, respectively, allows a sample's permittivity to be calculated. An analytical model describing the system response based on perturbation theory and quasi-static analysis of the electric field within the capillary is also presented and found to agree well with FEM simulations and experimental measurements of ethanol-water mixtures of various concentrations for low to moderate loss tangents of the liquid samples. We demonstrate the utility of this approach by measuring the complex permittivity of several bioliquids, including suspensions of red and white blood cells. These results represent a step towards a lab-on-a-chip device for the analysis of extremely small quantities of biological, toxic, explosive, and other liquid types at terahertz frequencies.

• OSTI ID: 22486349
• Journal Information: Applied Physics Letters, Vol. 107, Issue 3; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BLOOD CELLS
CRYSTALS
DIELECTRIC MATERIALS
DISTURBANCES
ELECTRIC FIELDS
ELECTROMAGNETIC FIELDS
ETHANOL
EXPLOSIVES
GHZ RANGE
LIQUIDS
LOSSES
MONITORING
PERMITTIVITY
RESONATORS
SILICON
SIMULATION
SLABS
SUSPENSIONS
TOXICITY
TUBES