17-03-2014, 06:46 PM
Abstract—Terahertz technology is considered a viable option
for medical imaging, since many biological and chemical agents
exhibit signatures in this spectral domain. Ultimately, large
biomolecules and protein strands will be accessible, enabled by
the coupling of THz science with near-field probes. In this
paper, we present the recent advances of our research
regarding a novel 2-D THz imaging system that it is intended to
be used for imaging and characterization of tissue and
biomolecule samples associated to brain functionality. Herein,
we specifically focus on the emitting elements of the system, by
studying two types of THz planar antennas for THz emission: a
rectangular and a bow-tie patch antenna working at 1 THz.
The aim and novelty of this work is to present an effective THz
antenna with high gain and to this end we use left-handed
materials for the substrate.
Keywords —THz patch antenna; metamaterial; split-ring
resonator.
I. INTRODUCTION
T he last decade, there has been a raised interest in the
THz regime by researchers working on biomedical
applications. The THz spectrum includes frequencies from
0.1 to 10 THz and lies between the microwaves and infrared
frequencies. This area of the electromagnetic spectrum was
for a long time neglected because of its difficulties to
approach it with optical or electronic methods. However,
recent advances in THz generation and detection encouraged
the research of THz applications, as THz spectroscopy,
imaging and sensing.
Specific characteristics of this radiation render it very
appealing to biomedicine and diagnostic medicine. A THz
photon does not carry enough energy (0.4 - 41 milli-eVs) to
ionize a biological molecule. In contrast to many popular
techniques that use electromagnetic radiation to image
biological tissues, T-rays have been characterized as “nonionizing”.
However, the thermal effects, which THz have on
biomolecules, depend on the length of the exposure and on
the power of the source [1].
Based on spectral specificity, most chemical substances
exhibit specific absorption features in the THz range.
Biomolecules naturally vibrate at terahertz frequencies, and
each has a distinct terahertz "fingerprint" [2]. In other words,
specific proteins absorb certain characteristic terahertz
frequencies, which change their molecular arrangement, or
conformation; sensors can then detect this absorption to
characterize the protein.
In this context, THz technology may add significant
knowledge to the understanding of brain function in health
and disease by providing biochemical profiling of various
neurotransmitters in various conditions. For example, recent
findings suggest that a distress in the equilibrium of different
excitatory and inhibitory neurotransmitters may be central to
the mechanisms of bipolar disorder [3]. Recent findings
support the abovementioned claims; in a novel study healthy
and diseased snap-frozen tissue samples obtained from three
regions of the human brain were distinguished using
terahertz (THz) spectroscopy [3]. Real-time THz
spectroscopy was used to detect biomolecule processes
associated with neurodegenerative phenomena [4]. Also,
recently it has been shown that terahertz (THz) spectroscopy
can be used to differentiate soft protein microstructures
which highly interest medical researchers, since they form
from naturally occurring proteins suggested to be involved
in several human diseases, such as Alzheimer’s disease [5].
In this paper, we present the recent advances of our
research regarding a novel 2-D THz imaging system [2] that
is intended to be used for imaging and characterization of
tissue and biomolecule samples associated to brain
functionality. Herein, we specifically focus on the emitting
elements of the system, by studying two types of THz planar
antennas for THz emission: a rectangular and a bow-tie
patch antenna working at 1 THz. The aim and novelty of this
work is to present an effective THz antenna with high gain
and to this end we use left-handed materials for the
substrate.
for medical imaging, since many biological and chemical agents
exhibit signatures in this spectral domain. Ultimately, large
biomolecules and protein strands will be accessible, enabled by
the coupling of THz science with near-field probes. In this
paper, we present the recent advances of our research
regarding a novel 2-D THz imaging system that it is intended to
be used for imaging and characterization of tissue and
biomolecule samples associated to brain functionality. Herein,
we specifically focus on the emitting elements of the system, by
studying two types of THz planar antennas for THz emission: a
rectangular and a bow-tie patch antenna working at 1 THz.
The aim and novelty of this work is to present an effective THz
antenna with high gain and to this end we use left-handed
materials for the substrate.
Keywords —THz patch antenna; metamaterial; split-ring
resonator.
I. INTRODUCTION
T he last decade, there has been a raised interest in the
THz regime by researchers working on biomedical
applications. The THz spectrum includes frequencies from
0.1 to 10 THz and lies between the microwaves and infrared
frequencies. This area of the electromagnetic spectrum was
for a long time neglected because of its difficulties to
approach it with optical or electronic methods. However,
recent advances in THz generation and detection encouraged
the research of THz applications, as THz spectroscopy,
imaging and sensing.
Specific characteristics of this radiation render it very
appealing to biomedicine and diagnostic medicine. A THz
photon does not carry enough energy (0.4 - 41 milli-eVs) to
ionize a biological molecule. In contrast to many popular
techniques that use electromagnetic radiation to image
biological tissues, T-rays have been characterized as “nonionizing”.
However, the thermal effects, which THz have on
biomolecules, depend on the length of the exposure and on
the power of the source [1].
Based on spectral specificity, most chemical substances
exhibit specific absorption features in the THz range.
Biomolecules naturally vibrate at terahertz frequencies, and
each has a distinct terahertz "fingerprint" [2]. In other words,
specific proteins absorb certain characteristic terahertz
frequencies, which change their molecular arrangement, or
conformation; sensors can then detect this absorption to
characterize the protein.
In this context, THz technology may add significant
knowledge to the understanding of brain function in health
and disease by providing biochemical profiling of various
neurotransmitters in various conditions. For example, recent
findings suggest that a distress in the equilibrium of different
excitatory and inhibitory neurotransmitters may be central to
the mechanisms of bipolar disorder [3]. Recent findings
support the abovementioned claims; in a novel study healthy
and diseased snap-frozen tissue samples obtained from three
regions of the human brain were distinguished using
terahertz (THz) spectroscopy [3]. Real-time THz
spectroscopy was used to detect biomolecule processes
associated with neurodegenerative phenomena [4]. Also,
recently it has been shown that terahertz (THz) spectroscopy
can be used to differentiate soft protein microstructures
which highly interest medical researchers, since they form
from naturally occurring proteins suggested to be involved
in several human diseases, such as Alzheimer’s disease [5].
In this paper, we present the recent advances of our
research regarding a novel 2-D THz imaging system [2] that
is intended to be used for imaging and characterization of
tissue and biomolecule samples associated to brain
functionality. Herein, we specifically focus on the emitting
elements of the system, by studying two types of THz planar
antennas for THz emission: a rectangular and a bow-tie
patch antenna working at 1 THz. The aim and novelty of this
work is to present an effective THz antenna with high gain
and to this end we use left-handed materials for the
substrate.