Detection of bioparticles is of great importance in electrophoresis, identification of biomass so... more Detection of bioparticles is of great importance in electrophoresis, identification of biomass sources, food and water safety, and other areas. It requires a proper model to describe bioparticles’ electromagnetic characteristics. A numerical study of Escherichia coli bacteria during their functional activity was carried out by using two different geometrical models for the cells that considered the bacteria as layered ellipsoids and layered spheres. It was concluded that during cell duplication, the change in the dielectric permittivity of the cell is high enough to be measured at radio frequencies of the order of 50 kHz. An experimental setup based on the capacitive Wheatstone bridge was designed to measure relative changes in permittivity during cell division. In this way, the theoretical model was validated by measuring the dielectric permittivity changes in a cell culture of Escherichia coli ATTC 8739 from WDCM 00012 Vitroids. The spheroidal model was confirmed to be more accurate.
The need for non-ionizing techniques for medical imaging applications has led to the use of micro... more The need for non-ionizing techniques for medical imaging applications has led to the use of microwave signals. Several systems have been introduced in recent years based on increasing the number of antennas and frequency bandwidth to obtain high resolution and good accuracy in locating objects. A novel microwave imaging system that reduces the number of required antennas for precise target location appropriate for medical applications is presented. The proposed system consists of four UWB extended gap ridge horn (EGRH) antennas covering the frequency band from 0.5 GHz to 1.5 GHz mounted on a cylindrical phantom that mimics the brain in an orthogonal set of two EGRH probes. This configuration has the ability to control both the longitudinal and transversal dimensions of the reconstructed target’s image, rather than controlling the spatial resolution, by increasing the frequency band that can be easily affected by medium losses. The system is tested numerically and experimentally by t...
Morphological microwave imaging has shown interesting results on reconstructing biological object... more Morphological microwave imaging has shown interesting results on reconstructing biological objects inside the human body, and these parameters represent their actual biological condition, but not their biological activity. In this paper, we propose a novel microwave technique to locate the low-frequency (f≃1 kHz) -modulated signals produced by a microtag mimicking an action potential and proved it in a cylindrical phantom of the brain region. A set of two combined UWB microwave applicators, operating in the 0.5 to 2.5 GHz frequency band and producing a nsec interrogation pulse, is able to focus its radiated field into a small region of the brain containing the microtag with a modulated photodiode. The illuminating UWB microwave field was first modulated by the low-frequency (f≃1 kHz) electrical signal produced by the photodiode, inducing modulated microwave currents into the microtag that reradiating back towards the focusing applicators. At the receiving end, the low-frequency (f≃1...
Optically pumped magnetometer with high spatial resolution magnetic guide for the detection of magnetic droplets in a microfluidic channel
New Journal of Physics
Quantum sensors provide unprecedented magnetic field detection sensitivities, enabling these to e... more Quantum sensors provide unprecedented magnetic field detection sensitivities, enabling these to extend the common magnetometry range of applications and environments of operation. In this framework, many applications also require high spatial resolution magnetic measurements for biomedical research, environmental monitoring and industrial production. In this regard, optically pumped magnetometers (OPMs) are considered as prominent candidates, but are impaired in size with micrometer scale magnetic particles, e.g. magnetic droplets. In order to address this limitation, here we study the effects of adding a micrometer-to-millimeter magnetic guide to a miniature OPM. This device is applied to detect Fe3O4 magnetic droplets flowing at rates up to 25 drop. s−1 in a microfluidic channel. The computed spatial resolution is 300 µm and the measured signal-to-noise ratio is larger than 15 dB for the different sizes of considered magnetic droplets.
IEEE Transactions on Instrumentation and Measurement
The combination of microwave and microfluidic technologies has the potential to enable wireless m... more The combination of microwave and microfluidic technologies has the potential to enable wireless monitoring and interaction with bioparticles, facilitating in this way the exploration of a still largely uncharted territory at the intersection of biology, communication engineering and microscale physics. Opportunely, the scientific and technical requirements of microfluidics and microwave techniques converge to the need of system miniaturization to achieve the required sensitivity levels. This work, therefore, presents the design and optimization of a measurement system for the detection of bioparticles over the frequency range 0.01 to 10 GHz, with different coplanar electrodes configurations on a microfluidic platform. The design of the measurement signal-chain setup is optimized for a novel real-time superheterodyne microwave detection system. In particular, signal integrity is achieved by means of a microwaveshielded chamber, which is protected from external electromagnetic interference that may potentially impact the coplanar electrodes mounted on the microfluidic device. Additionally, analytical expressions and experimental validation of the systemlevel performance are provided and discussed for the different designs of the coplanar electrodes. This technique is applied to measure the electrical field perturbation produced by 10 µm polystyrene beads with a concentration of 10 5 beads/mL, and flowing at a rate of 10 µL/min. The achieved SNR is in the order of 40 dB for the three coplanar electrodes considered.
Nonlinear effects in the radio front-end can degrade communication quality and system performance... more Nonlinear effects in the radio front-end can degrade communication quality and system performance. In this paper we present a new design technique for reconfigurable antennas that minimizes the nonlinear distortion and maximizes power efficiency through the minimization of the coupling between the internal switching ports and the external feeding ports. As a nonlinear design and validation instance, we present the nonlinear characterization up to 50 GHz of a PIN diode commonly used as a switch for reconfigurable devices in the microwave band. Nonlinear models are extracted through X-parameter measurements supported by accurate calibration and de-embedding procedures. Nonlinear switch models are validated by S-parameter measurements in the low power signal regime and by harmonic measurements in the large-signal regime and are further used to predict the measured nonlinearities of a reconfigurable antenna. These models have the desired particularity of being integrated straightforward...
The investigation of the electromagnetic properties of biological particles in microfluidic platf... more The investigation of the electromagnetic properties of biological particles in microfluidic platforms may enable wireless monitoring and interaction with functional activity of microorganisms. Of high relevance is the membrane potential as it is one of the most important parameters of living cells. In particular, the complex mechanisms of the cell’s membrane potential are comparable to the dynamics of bacteria membranes, providing a simplified platform for advancing the current techniques and knowledge of general bio-particle dynamics. In this work, we provide a theoretical analysis and experimental results on the microwave detection of bacteria on a microfluidic-based framework for sensing the membrane potential of bacteria. The results enable to further advance the state-of-the-art of electromagnetic bacteria sensing and microfluidic control, and their implication for measuring and interacting with the cell and its membrane potentials, which is of great importance for developing n...
Carefully check the page proofs (and coordinate with all authors); additional changes or updates ... more Carefully check the page proofs (and coordinate with all authors); additional changes or updates WILL NOT be accepted after the article is published online/print in its final form. Please check author names and affiliations, funding, as well as the overall article for any errors prior to sending in your author proof corrections. Your article has been peer reviewed, accepted as final, and sent in to IEEE. No text changes have been made to the main part of the article as dictated by the editorial level of service for your publication. • Author: We cannot accept new source files as corrections for your article. If possible, please annotate the PDF proof we have sent you with your corrections and upload it via the Author Gateway. Alternatively, you may send us your corrections in list format. You may also upload revised graphics via the Author Gateway. • Authors are required to pay page charges for correspondence and regular articles. The policy is: For correspondence articles a charge is required for page 6. The first 5 pages incur no fee. • Articles submitted before January 21, 2020 will be subject to the following page charge policy: For regular articles, page charges are due for all pages beyond page 8. There is no fee for the first 8 pages. For regular articles submitted after January 21, 2020, page charges are due for all pages beyond page 10. There is no fee for the first 10 pages. • If you cannot pay these charges you must advise us and/or shorten your article accordingly. • Page Limits: No regular article can exceed 15 pages. Correspondence articles cannot exceed 6 pages. Note the page charge policy for each of these.
IEEE Transactions on Antennas and Propagation, 1985
A numerical method and experimental technique for microwave imaging of inhomogeuons bodies is pre... more A numerical method and experimental technique for microwave imaging of inhomogeuons bodies is presented. This method is based on the interpretation of the diffraction phenomena and leads to tomographic reconstruction of the body under investigation. Various nnmerical examples are given on spatial impulse response, recognition of dielectric rods, inhomogeneous bodies, and simulated human arm. Different experimental results on dielectric rods and isolated animal organs are also given.
A novel multiple marker level-set method is introduced for Direct Numerical Simulation of deforma... more A novel multiple marker level-set method is introduced for Direct Numerical Simulation of deformable fluid particles (bubbles and droplets), which is integrated in a finite-volume framework on collocated unstructured grids. Each fluid particle is described by a separate level-set function, thus, different interfaces can be solved in the same control volume, avoiding artificial and potentially unphysical coalescence of fluid particles. Therefore, bubbles or droplets are able to approach each other closely, within the size of one grid cell, and can even collide. The proposed algorithm is developed in the context of the conservative level-set method, whereas, surface tension is modeled by the continuous surface force approach. The pressure-velocity coupling is solved by the fractional-step projection method. For validation of the proposed numerical method, the gravity-driven impact of a droplet on a liquid-liquid interface is studied; then, the binary droplet collision with bouncing outcome is examined, and finally, it is applied on simulation of gravity-driven bubbly flow in a vertical column.
Detection of bioparticles is of great importance in electrophoresis, identification of biomass so... more Detection of bioparticles is of great importance in electrophoresis, identification of biomass sources, food and water safety, and other areas. It requires a proper model to describe bioparticles’ electromagnetic characteristics. A numerical study of Escherichia coli bacteria during their functional activity was carried out by using two different geometrical models for the cells that considered the bacteria as layered ellipsoids and layered spheres. It was concluded that during cell duplication, the change in the dielectric permittivity of the cell is high enough to be measured at radio frequencies of the order of 50 kHz. An experimental setup based on the capacitive Wheatstone bridge was designed to measure relative changes in permittivity during cell division. In this way, the theoretical model was validated by measuring the dielectric permittivity changes in a cell culture of Escherichia coli ATTC 8739 from WDCM 00012 Vitroids. The spheroidal model was confirmed to be more accurate.
The need for non-ionizing techniques for medical imaging applications has led to the use of micro... more The need for non-ionizing techniques for medical imaging applications has led to the use of microwave signals. Several systems have been introduced in recent years based on increasing the number of antennas and frequency bandwidth to obtain high resolution and good accuracy in locating objects. A novel microwave imaging system that reduces the number of required antennas for precise target location appropriate for medical applications is presented. The proposed system consists of four UWB extended gap ridge horn (EGRH) antennas covering the frequency band from 0.5 GHz to 1.5 GHz mounted on a cylindrical phantom that mimics the brain in an orthogonal set of two EGRH probes. This configuration has the ability to control both the longitudinal and transversal dimensions of the reconstructed target’s image, rather than controlling the spatial resolution, by increasing the frequency band that can be easily affected by medium losses. The system is tested numerically and experimentally by t...
Morphological microwave imaging has shown interesting results on reconstructing biological object... more Morphological microwave imaging has shown interesting results on reconstructing biological objects inside the human body, and these parameters represent their actual biological condition, but not their biological activity. In this paper, we propose a novel microwave technique to locate the low-frequency (f≃1 kHz) -modulated signals produced by a microtag mimicking an action potential and proved it in a cylindrical phantom of the brain region. A set of two combined UWB microwave applicators, operating in the 0.5 to 2.5 GHz frequency band and producing a nsec interrogation pulse, is able to focus its radiated field into a small region of the brain containing the microtag with a modulated photodiode. The illuminating UWB microwave field was first modulated by the low-frequency (f≃1 kHz) electrical signal produced by the photodiode, inducing modulated microwave currents into the microtag that reradiating back towards the focusing applicators. At the receiving end, the low-frequency (f≃1...
Optically pumped magnetometer with high spatial resolution magnetic guide for the detection of magnetic droplets in a microfluidic channel
New Journal of Physics
Quantum sensors provide unprecedented magnetic field detection sensitivities, enabling these to e... more Quantum sensors provide unprecedented magnetic field detection sensitivities, enabling these to extend the common magnetometry range of applications and environments of operation. In this framework, many applications also require high spatial resolution magnetic measurements for biomedical research, environmental monitoring and industrial production. In this regard, optically pumped magnetometers (OPMs) are considered as prominent candidates, but are impaired in size with micrometer scale magnetic particles, e.g. magnetic droplets. In order to address this limitation, here we study the effects of adding a micrometer-to-millimeter magnetic guide to a miniature OPM. This device is applied to detect Fe3O4 magnetic droplets flowing at rates up to 25 drop. s−1 in a microfluidic channel. The computed spatial resolution is 300 µm and the measured signal-to-noise ratio is larger than 15 dB for the different sizes of considered magnetic droplets.
IEEE Transactions on Instrumentation and Measurement
The combination of microwave and microfluidic technologies has the potential to enable wireless m... more The combination of microwave and microfluidic technologies has the potential to enable wireless monitoring and interaction with bioparticles, facilitating in this way the exploration of a still largely uncharted territory at the intersection of biology, communication engineering and microscale physics. Opportunely, the scientific and technical requirements of microfluidics and microwave techniques converge to the need of system miniaturization to achieve the required sensitivity levels. This work, therefore, presents the design and optimization of a measurement system for the detection of bioparticles over the frequency range 0.01 to 10 GHz, with different coplanar electrodes configurations on a microfluidic platform. The design of the measurement signal-chain setup is optimized for a novel real-time superheterodyne microwave detection system. In particular, signal integrity is achieved by means of a microwaveshielded chamber, which is protected from external electromagnetic interference that may potentially impact the coplanar electrodes mounted on the microfluidic device. Additionally, analytical expressions and experimental validation of the systemlevel performance are provided and discussed for the different designs of the coplanar electrodes. This technique is applied to measure the electrical field perturbation produced by 10 µm polystyrene beads with a concentration of 10 5 beads/mL, and flowing at a rate of 10 µL/min. The achieved SNR is in the order of 40 dB for the three coplanar electrodes considered.
Nonlinear effects in the radio front-end can degrade communication quality and system performance... more Nonlinear effects in the radio front-end can degrade communication quality and system performance. In this paper we present a new design technique for reconfigurable antennas that minimizes the nonlinear distortion and maximizes power efficiency through the minimization of the coupling between the internal switching ports and the external feeding ports. As a nonlinear design and validation instance, we present the nonlinear characterization up to 50 GHz of a PIN diode commonly used as a switch for reconfigurable devices in the microwave band. Nonlinear models are extracted through X-parameter measurements supported by accurate calibration and de-embedding procedures. Nonlinear switch models are validated by S-parameter measurements in the low power signal regime and by harmonic measurements in the large-signal regime and are further used to predict the measured nonlinearities of a reconfigurable antenna. These models have the desired particularity of being integrated straightforward...
The investigation of the electromagnetic properties of biological particles in microfluidic platf... more The investigation of the electromagnetic properties of biological particles in microfluidic platforms may enable wireless monitoring and interaction with functional activity of microorganisms. Of high relevance is the membrane potential as it is one of the most important parameters of living cells. In particular, the complex mechanisms of the cell’s membrane potential are comparable to the dynamics of bacteria membranes, providing a simplified platform for advancing the current techniques and knowledge of general bio-particle dynamics. In this work, we provide a theoretical analysis and experimental results on the microwave detection of bacteria on a microfluidic-based framework for sensing the membrane potential of bacteria. The results enable to further advance the state-of-the-art of electromagnetic bacteria sensing and microfluidic control, and their implication for measuring and interacting with the cell and its membrane potentials, which is of great importance for developing n...
Carefully check the page proofs (and coordinate with all authors); additional changes or updates ... more Carefully check the page proofs (and coordinate with all authors); additional changes or updates WILL NOT be accepted after the article is published online/print in its final form. Please check author names and affiliations, funding, as well as the overall article for any errors prior to sending in your author proof corrections. Your article has been peer reviewed, accepted as final, and sent in to IEEE. No text changes have been made to the main part of the article as dictated by the editorial level of service for your publication. • Author: We cannot accept new source files as corrections for your article. If possible, please annotate the PDF proof we have sent you with your corrections and upload it via the Author Gateway. Alternatively, you may send us your corrections in list format. You may also upload revised graphics via the Author Gateway. • Authors are required to pay page charges for correspondence and regular articles. The policy is: For correspondence articles a charge is required for page 6. The first 5 pages incur no fee. • Articles submitted before January 21, 2020 will be subject to the following page charge policy: For regular articles, page charges are due for all pages beyond page 8. There is no fee for the first 8 pages. For regular articles submitted after January 21, 2020, page charges are due for all pages beyond page 10. There is no fee for the first 10 pages. • If you cannot pay these charges you must advise us and/or shorten your article accordingly. • Page Limits: No regular article can exceed 15 pages. Correspondence articles cannot exceed 6 pages. Note the page charge policy for each of these.
IEEE Transactions on Antennas and Propagation, 1985
A numerical method and experimental technique for microwave imaging of inhomogeuons bodies is pre... more A numerical method and experimental technique for microwave imaging of inhomogeuons bodies is presented. This method is based on the interpretation of the diffraction phenomena and leads to tomographic reconstruction of the body under investigation. Various nnmerical examples are given on spatial impulse response, recognition of dielectric rods, inhomogeneous bodies, and simulated human arm. Different experimental results on dielectric rods and isolated animal organs are also given.
A novel multiple marker level-set method is introduced for Direct Numerical Simulation of deforma... more A novel multiple marker level-set method is introduced for Direct Numerical Simulation of deformable fluid particles (bubbles and droplets), which is integrated in a finite-volume framework on collocated unstructured grids. Each fluid particle is described by a separate level-set function, thus, different interfaces can be solved in the same control volume, avoiding artificial and potentially unphysical coalescence of fluid particles. Therefore, bubbles or droplets are able to approach each other closely, within the size of one grid cell, and can even collide. The proposed algorithm is developed in the context of the conservative level-set method, whereas, surface tension is modeled by the continuous surface force approach. The pressure-velocity coupling is solved by the fractional-step projection method. For validation of the proposed numerical method, the gravity-driven impact of a droplet on a liquid-liquid interface is studied; then, the binary droplet collision with bouncing outcome is examined, and finally, it is applied on simulation of gravity-driven bubbly flow in a vertical column.
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