Sweat,as a biofluid with the potential for noninvasive collection,provides profound insights into human health conditions,because it contains various chemicals and information to be utilized for the monitoring of well...Sweat,as a biofluid with the potential for noninvasive collection,provides profound insights into human health conditions,because it contains various chemicals and information to be utilized for the monitoring of well-being,stress levels,exercise,and nutrition.Recently,wearable sweat sensors have been developed as a promising substitute to conventional laboratory sweat detection methods.Such sensors are promising to realize low-cost,real-time,in situ sweat measurements,and provide great opportunities for health status evaluation analysis based on personalized big data.This review first presents an overview of wearable sweat sensors from the perspective of basic components,including materials and structures for specific sensing applications and modalities.Current strategies and specific methods of the fabrication of wearable power management are also summarized.Finally,current challenges and future directions of wearable sweat sensors are discussed.展开更多
Diffuse optical spectroscopy is a relatively new,noninvasive and nonionizing technique for breast cancer diagnosis.In the present study,we have introduced a novel handheld diffuse optical breast scan(DOB-Scan)probe to...Diffuse optical spectroscopy is a relatively new,noninvasive and nonionizing technique for breast cancer diagnosis.In the present study,we have introduced a novel handheld diffuse optical breast scan(DOB-Scan)probe to measure optical properties of the breast in vivo and create functional and compositional images of the tissue.In addition,the probe gives more information about breast tissue's constituents,which helps distinguish a healthy and cancerous tissue.Two symmetrical light sources,each including four different wavelengths,are used to illuminate the breast tissue.A high-resolution linear array detector measures the intensity of the back-scattered photons at different radial destinations from the illumination sources on the surface of the breast tissue,and a unique image reconstruction algorithm is used to create four cross-sectional images for four different wavelengths.Different fromfiber optic-based illumination techniques,the proposed method in this paper integrates multi-wavelength light-emitting diodes to act as pencil beam sources into a scattering medium like breast tissue.This unique design and its compact structure reduce the complexity,size and cost of a potential probe.Although the introduced technique miniaturizes the probe,this study points to the reliability of this technique in the phantom study and clinical breast imaging.We have received ethical approval to test the DOB-Scan probe on patients and we are currently testing the DOB-Scan probe on subjects who are diagnosed with breast cancer.展开更多
Diffuse Optical Spectroscopy(DOS)is a promising non-invasive and non-ionizing technique for breast anomaly detection.In this study,we have developed a new handheld DOS probe to measure optical properties of breast tis...Diffuse Optical Spectroscopy(DOS)is a promising non-invasive and non-ionizing technique for breast anomaly detection.In this study,we have developed a new handheld DOS probe to measure optical properties of breast tissue.In the proposed probe,the breast tissue is illuminated with four near infrared(NIR)wavelengths light emitting diodes(LED),which are encapsulated in a package(eLEDs),and two PIN photodiodes measure the intensity of the scattered photons at two di®erent locations.The proposed technique of using eLEDs is introduced,in order to have a multi-wavelength pointed-beam illumination source instead of using the laser-coupledflberoptic technique,which increases the complexity,size,and cost of the probe.Despite the fact that the proposed technique miniaturizes the probe and reduces the complexity of the DOS,the study proves that it is accurate and reliable in measuring optical properties of the tissue.The measurements are performed at the rate of 10 Hz which is suitable for dynamic measurement of biological activity,in-vivo.The multi-spectral evaluation algorithm is used to reconstruct four main absorber concentrations in the breast including oxy-hemoglobin(cHb),deoxy-hemoglobin(cHbO_(2)),water(cH2O),fat(cFat),and average scattering coeficient of the medium,as well as concentration changes in Hb(cHb)and HbO_(2)(cHbO_(2)).Although the probe is designed for breast cancer diagnosis,it can be used in a wide range of applications for both static and dynamic measurements such as functional brain imaging.A series of phantoms,comprised of Delrinr,Intralipidr,PierceTM and Black ink,are used to verify performance of the device.The probe will be tested on human subjects,in-vivo,in the next phase.展开更多
The electric power transfer capability on the Manitoba-Ontario interconnection depends on various system operating conditions such as area generation patterns and ambient temperatures. This work models the power netwo...The electric power transfer capability on the Manitoba-Ontario interconnection depends on various system operating conditions such as area generation patterns and ambient temperatures. This work models the power network as a black-box function, which is evaluated with the system reliability analysis techniques to determine the maximum transfer capability under a given operating condition. A metamodel or an approximation model of the maximized power transfer capability is built based on the sampled system responses and optimized with respect to the corresponding operating conditions. An optimal metamodel is implemented as a prototype software tool, PTCanalyzer, and applied to Manitoba-Ontario interconnection power transfer calculations. This optimized metamodel technique provides an in-depth understanding of the dependency of the power transfer capability on system operating conditions and proves to be an effective tool in optimizing the operation planning of the interconnection for a given power system configuration. The PTCanalyzer has the potential to be used for optimization of other power network interconnections.展开更多
The present study aims to develop a novel optimal design of hybrid energy systems based on exergy and lifecycle concepts using genetic algorithms.The model consists of both stand-alone and on-grid options with scenari...The present study aims to develop a novel optimal design of hybrid energy systems based on exergy and lifecycle concepts using genetic algorithms.The model consists of both stand-alone and on-grid options with scenarios for exchanging energy with the grid.The objectives include cost minimization or benefit maximization primarily,and lifecycle exergy efficiency,i.e.,cost as the sustainability index secondarily.This research considers renewable sources such as solar,wind,hydropower,and hydrogen production and storage in addition to conventional diesel generators.The optimization was performed subject to weather conditions and solar radiation profiles,demand,and environmental or economic aspects.Also,the model contains various modules such as water-heating,waste energy utilization,as well as the options of power exchange with the distribution network and injection of hydrogen produced from excess renewable sources into the gas network.The application was demonstrated in a case study,where specific demands and the climate of Tehran were assumed.The case study considers four scenarios,including standalone,completely on-grid,on-grid with a non-backup generator,and on-grid without an energy sale option.The first optimal objective,the levelized unit cost of energy for the standalone system,is$0.22 per kWh.Moreover,the second optimal objective,the lifecycle exergy cost,ranges from 1.93 to 4.13 in different grid-connection states.展开更多
Evaporative cooling(EC)is an ancient technique that is usually suitable for hot and dry climatic conditions due to the potential of water vapor evaporation.In this study,three kinds of evaporative cooling systems such...Evaporative cooling(EC)is an ancient technique that is usually suitable for hot and dry climatic conditions due to the potential of water vapor evaporation.In this study,three kinds of evaporative cooling systems such as direct EC(DEC),indirect EC(IEC),and Maisotsenko cycle EC(MEC)were locally developed at lab-scale.The performance of the systems was evaluated and compared for agricultural storage and livestock air-conditioning application in Pakistan.The experiments were performed for climatic conditions of Multan city(Pakistan)and the data were collected for hourly and daily basis.According to the results,it was observed that the DEC system has the ability to reduce the temperature of ambient air to an average of 8.5℃.Whilst IEC and MEC systems were able to drop the temperature of ambient air to an average of 6.8℃and 8.9℃,respectively.As per the results,the DEC system remained behind to provide desired conditions for livestock and agricultural product storage applications due to excessive humidity.On the other hand,the IEC and MEC systems can achieve the desired conditions for livestock application,but could not provide feasible conditions for various fruits and vegetable storage.The study concludes that hybrid EC systems can be developed to provide desired conditions for a wide range of applications under varying climatic conditions.展开更多
The small dimensions of microfabricated devices present challenges in applications such as inertial sensing,where a larger proofmass is necessary for enhanced sensitivity.An effective approach to addressing the limita...The small dimensions of microfabricated devices present challenges in applications such as inertial sensing,where a larger proofmass is necessary for enhanced sensitivity.An effective approach to addressing the limitations of linear sensing is to use nonlinear mechanisms that adapt the device’s response according to different operating conditions.This paper introduces a new nonlinear spring mechanism for use in microsensors that harnesses the buckling phenomenon to achieve stiffness softening.The proposed mechanism utilizes a micro-arm to apply an eccentric axial load to an inclined beam,causing it to buckle in a controlled manner under a specified load.Once buckled,linear springs dominate the response of the system.We demonstrate that this method results in a smaller bias displacement compared to previously reported techniques based on snap-through behaviour,leading to potential reductions in device size and improvements in operational range.The behaviour is analytically modelled and verified through simulations.A prototype device was designed and microfabricated to experimentally validate the design principles.Compared to pre-curved nonlinear springs,the proposed design results in an 11-fold reduction in bias force,a 100-fold reduction in bias displacement,and a reduction in mechanical stiffness by a factor of 520.These results were verified through experiments conducted on a microfabricated accelerometer with an on-chip optical interferometer.Test results reveal an extended linear range of better than 150mg,a bias force of 0.3 mN,and a bias displacement of 10μm,measured with an integrated optical interferometer with a displacement noise floor of 40 pm/√ Hz p at 2 Hz and sensitivity of 194°=mg.展开更多
Greenhouse solar-energy driven desalination technology is potentially well suited for supplying water and small scale irrigation in remote and/or rural areas, and for avoiding over-exploitation of available water reso...Greenhouse solar-energy driven desalination technology is potentially well suited for supplying water and small scale irrigation in remote and/or rural areas, and for avoiding over-exploitation of available water resources. The efficiency and productivity of these systems are however low, in part because the heat of evaporation has to be transferred as waste heat to ambient air during condensation. In order to maximize energy regeneration during condensation we propose an educator based system that lowers the evaporation process temperature by reducing pressure. The feasibility of the educator assisted passive solar desalination system is investigated using a detailed computational fluid dynamics analysis complemented by experiments. The study focuses in particular on the ability of the new design to lower the required evaporation temperature and thereby reduce the energy intensity of the process. Two configurations, with open and closed educator, are investigated and a detailed analysis of the thermofluid processes is presented. The configuration with a closed educator installed outside the evaporation chamber shows very promising performance. The proposed system can maintain the maximum temperature and pressure in theevaporation chamber below the desirable temperature and pressure thresholds （30 ℃ and 5 kPa）. The analysis and experimental data also show it is possible to further reduce energy requirements by reducing the motive water flow rates.展开更多
The bipolar low-voltage DC(LVDC) distribution system has become a prospective solution to better integration of renewables and improvement of system efficiency and reliability. However, it also faces the challenge of ...The bipolar low-voltage DC(LVDC) distribution system has become a prospective solution to better integration of renewables and improvement of system efficiency and reliability. However, it also faces the challenge of power and voltage imbalance between two poles. To solve this problem, an interface converter with bipolar asymmetrical operating capabilities is applied in this paper. The steady-state models of the bipolar LVDC distribution system equipped with this interface converter in the gridconnected mode and off-grid mode are analyzed. A control scheme based on DC offset injection at the secondary side of the interface converter is proposed, enabling the bipolar LVDC distribution system to realize the unbalanced power transfer between two poles in the grid-connected mode and maintain the inherentpole voltage balance in the off-grid mode. Furthermore, this paper also proposes a primary-side DC offset injection control scheme according to the analysis of the magnetic circuit model, which can eliminate the DC bias flux caused by the secondaryside DC offset. Thereby, the potential core magnetic saturation and overcurrent issues can be prevented, ensuring the safety of the interface converter and distribution system. Detailed simulations based on the proposed control scheme are conducted to validate the function of power and voltage balance under the operation conditions of different DC loads.展开更多
In this study,based on inspiration drawn from origami and the suction mechanism of leeches,a dry electrode is developed for reliable blood pressure(BP)monitoring.The leech-inspired suction mechanism generated a local ...In this study,based on inspiration drawn from origami and the suction mechanism of leeches,a dry electrode is developed for reliable blood pressure(BP)monitoring.The leech-inspired suction mechanism generated a local soft vacuum facilitating appropriate contact with the human skin.Subsequently,an electrocardiogram(ECG)sensor,termed a leech-inspired origami(LIO)sensor,was constructed using the developed dry electrode.The LIO with a sensing robot system ensures reliable ECG signals with a signal-to-noise ratio of 21.7±0.56 dB.From the paired detection of ECG and photoplethysmography(PPG)through human-robot interaction,BP monitoring was demonstrated.The average difference of the systolic BP between that estimated by the sensing robot and that monitored by the sphygmomanometer was 0.03 mmHg,indicating the reliable BP monitoring ability of the sensing robot.The LIO sensing system inspired by origami and leech behaviors makes BP sensing tools feasible,which in turn would further the development of a remote healthcare monitoring robotic system.展开更多
A pressure monitoring structure is a very useful element for a wearable device for health monitoring and sports biomechanics.While pressure sensors have been studied extensively,battery-free functions working in wirel...A pressure monitoring structure is a very useful element for a wearable device for health monitoring and sports biomechanics.While pressure sensors have been studied extensively,battery-free functions working in wireless detection have not been studied much.Here,we report a 3D-structured origami-based architecture sensor for wireless pressure monitoring.We developed an architectured platform for wireless pressure sensing through inductorcapacitor(LC)sensors and a monopole antenna.A personalized smart insole with Miura-ori origami designs has been 3D printed together with conductive 3D printed sensors seamlessly.Wireless monitoring of resonant frequency and intensity changes of LC sensors have been demonstrated to monitor foot pressure for different postures.The sensitivity of the wireless pressure sensor is tunable from 15.7 to 2.1 MHz/kPa in the pressure ranges from 0 to 9 kPa and from 10 to 40 kPa,respectively.The proposed wireless pressure-sensing platform can be utilized for various applications such as orthotics,prosthetics,and sports gear.展开更多
We present here a 3D-printed pressure mapping mat,equipped with customizable architecture sensors,that offers a cost-effective and adaptable solution,overcoming the size constraints and sensing accuracy issues commonl...We present here a 3D-printed pressure mapping mat,equipped with customizable architecture sensors,that offers a cost-effective and adaptable solution,overcoming the size constraints and sensing accuracy issues commonly associated with existing commercial pressure mats across various fields,such as healthcare and sports applications.Leveraging a pillar-origami structure,the demonstrated sensor offers multifaceted stiffness properties,effectively filtering skin deformations and enabling capacitive pressure sensing.Notably,the sensor’s detection range can be finely tuned,spanning from 70 to 2500 kPa,with a sensitivity range between 0.01 kPa^(−1) and 0.0002 kPa^(−1),and an impressive response time of just 800 milliseconds.Furthermore,the inclusion of a modular sensor array enhances maintenance and allows for greater flexibility in shaping and enhancing the device’s resolution.This technology finds practical applications in wireless foot pressure mapping and sports protection pads,marking a significant milestone in the advancement of flexible and custom-shaped pressure sensor technology.展开更多
基金the National Natural Science Foundation of China(Nos.51975513 and 52105593)the Natural Science Foundation of Zhejiang Province,China(No.LR20E050003)and the Major Research Plan of Ningbo Innovation 2025(No.2020Z022).
文摘Sweat,as a biofluid with the potential for noninvasive collection,provides profound insights into human health conditions,because it contains various chemicals and information to be utilized for the monitoring of well-being,stress levels,exercise,and nutrition.Recently,wearable sweat sensors have been developed as a promising substitute to conventional laboratory sweat detection methods.Such sensors are promising to realize low-cost,real-time,in situ sweat measurements,and provide great opportunities for health status evaluation analysis based on personalized big data.This review first presents an overview of wearable sweat sensors from the perspective of basic components,including materials and structures for specific sensing applications and modalities.Current strategies and specific methods of the fabrication of wearable power management are also summarized.Finally,current challenges and future directions of wearable sweat sensors are discussed.
基金The Natural Sciences and Engineering Research Council of Canada(NSERC)provided partialfi-nancial support for this project.The authors thank Dr.Rhonda Janzen(with the Jim Pattison Outpatient Care and Surgery Center),Dr.Mojgan Jenab,M.Sc.student Zahra Haeiri(both from SFU)for conducting the clinical test,Sepideh M.Moqadam for her input in case design and M.Sc.student Mi Zhou at SFU to review and edit the paper.
文摘Diffuse optical spectroscopy is a relatively new,noninvasive and nonionizing technique for breast cancer diagnosis.In the present study,we have introduced a novel handheld diffuse optical breast scan(DOB-Scan)probe to measure optical properties of the breast in vivo and create functional and compositional images of the tissue.In addition,the probe gives more information about breast tissue's constituents,which helps distinguish a healthy and cancerous tissue.Two symmetrical light sources,each including four different wavelengths,are used to illuminate the breast tissue.A high-resolution linear array detector measures the intensity of the back-scattered photons at different radial destinations from the illumination sources on the surface of the breast tissue,and a unique image reconstruction algorithm is used to create four cross-sectional images for four different wavelengths.Different fromfiber optic-based illumination techniques,the proposed method in this paper integrates multi-wavelength light-emitting diodes to act as pencil beam sources into a scattering medium like breast tissue.This unique design and its compact structure reduce the complexity,size and cost of a potential probe.Although the introduced technique miniaturizes the probe,this study points to the reliability of this technique in the phantom study and clinical breast imaging.We have received ethical approval to test the DOB-Scan probe on patients and we are currently testing the DOB-Scan probe on subjects who are diagnosed with breast cancer.
文摘Diffuse Optical Spectroscopy(DOS)is a promising non-invasive and non-ionizing technique for breast anomaly detection.In this study,we have developed a new handheld DOS probe to measure optical properties of breast tissue.In the proposed probe,the breast tissue is illuminated with four near infrared(NIR)wavelengths light emitting diodes(LED),which are encapsulated in a package(eLEDs),and two PIN photodiodes measure the intensity of the scattered photons at two di®erent locations.The proposed technique of using eLEDs is introduced,in order to have a multi-wavelength pointed-beam illumination source instead of using the laser-coupledflberoptic technique,which increases the complexity,size,and cost of the probe.Despite the fact that the proposed technique miniaturizes the probe and reduces the complexity of the DOS,the study proves that it is accurate and reliable in measuring optical properties of the tissue.The measurements are performed at the rate of 10 Hz which is suitable for dynamic measurement of biological activity,in-vivo.The multi-spectral evaluation algorithm is used to reconstruct four main absorber concentrations in the breast including oxy-hemoglobin(cHb),deoxy-hemoglobin(cHbO_(2)),water(cH2O),fat(cFat),and average scattering coeficient of the medium,as well as concentration changes in Hb(cHb)and HbO_(2)(cHbO_(2)).Although the probe is designed for breast cancer diagnosis,it can be used in a wide range of applications for both static and dynamic measurements such as functional brain imaging.A series of phantoms,comprised of Delrinr,Intralipidr,PierceTM and Black ink,are used to verify performance of the device.The probe will be tested on human subjects,in-vivo,in the next phase.
文摘The electric power transfer capability on the Manitoba-Ontario interconnection depends on various system operating conditions such as area generation patterns and ambient temperatures. This work models the power network as a black-box function, which is evaluated with the system reliability analysis techniques to determine the maximum transfer capability under a given operating condition. A metamodel or an approximation model of the maximized power transfer capability is built based on the sampled system responses and optimized with respect to the corresponding operating conditions. An optimal metamodel is implemented as a prototype software tool, PTCanalyzer, and applied to Manitoba-Ontario interconnection power transfer calculations. This optimized metamodel technique provides an in-depth understanding of the dependency of the power transfer capability on system operating conditions and proves to be an effective tool in optimizing the operation planning of the interconnection for a given power system configuration. The PTCanalyzer has the potential to be used for optimization of other power network interconnections.
文摘The present study aims to develop a novel optimal design of hybrid energy systems based on exergy and lifecycle concepts using genetic algorithms.The model consists of both stand-alone and on-grid options with scenarios for exchanging energy with the grid.The objectives include cost minimization or benefit maximization primarily,and lifecycle exergy efficiency,i.e.,cost as the sustainability index secondarily.This research considers renewable sources such as solar,wind,hydropower,and hydrogen production and storage in addition to conventional diesel generators.The optimization was performed subject to weather conditions and solar radiation profiles,demand,and environmental or economic aspects.Also,the model contains various modules such as water-heating,waste energy utilization,as well as the options of power exchange with the distribution network and injection of hydrogen produced from excess renewable sources into the gas network.The application was demonstrated in a case study,where specific demands and the climate of Tehran were assumed.The case study considers four scenarios,including standalone,completely on-grid,on-grid with a non-backup generator,and on-grid without an energy sale option.The first optimal objective,the levelized unit cost of energy for the standalone system,is$0.22 per kWh.Moreover,the second optimal objective,the lifecycle exergy cost,ranges from 1.93 to 4.13 in different grid-connection states.
基金funded by Bahauddin Zakariya University,Multan,Pakistan under the Director Research/ORIC grant entitled“Development and performance evaluation of prototypes of direct and indirect evaporative cooling-based air-conditioning systems”。
文摘Evaporative cooling(EC)is an ancient technique that is usually suitable for hot and dry climatic conditions due to the potential of water vapor evaporation.In this study,three kinds of evaporative cooling systems such as direct EC(DEC),indirect EC(IEC),and Maisotsenko cycle EC(MEC)were locally developed at lab-scale.The performance of the systems was evaluated and compared for agricultural storage and livestock air-conditioning application in Pakistan.The experiments were performed for climatic conditions of Multan city(Pakistan)and the data were collected for hourly and daily basis.According to the results,it was observed that the DEC system has the ability to reduce the temperature of ambient air to an average of 8.5℃.Whilst IEC and MEC systems were able to drop the temperature of ambient air to an average of 6.8℃and 8.9℃,respectively.As per the results,the DEC system remained behind to provide desired conditions for livestock and agricultural product storage applications due to excessive humidity.On the other hand,the IEC and MEC systems can achieve the desired conditions for livestock application,but could not provide feasible conditions for various fruits and vegetable storage.The study concludes that hybrid EC systems can be developed to provide desired conditions for a wide range of applications under varying climatic conditions.
基金financially supported by the Canadian Space Agency(CSA)CMC Microsystems,the manager of the FABrIC project,which is funded by the Government of Canada,for providing CAD tools and test equipment that facilitated this research+2 种基金the 4D LABS core facility at Simon Fraser University,supported by the Canada Foundation for Innovation(CFI)British Columbia Knowledge Development Fund(BCKDF)Pacific Economic Development Canada(PacifiCan).
文摘The small dimensions of microfabricated devices present challenges in applications such as inertial sensing,where a larger proofmass is necessary for enhanced sensitivity.An effective approach to addressing the limitations of linear sensing is to use nonlinear mechanisms that adapt the device’s response according to different operating conditions.This paper introduces a new nonlinear spring mechanism for use in microsensors that harnesses the buckling phenomenon to achieve stiffness softening.The proposed mechanism utilizes a micro-arm to apply an eccentric axial load to an inclined beam,causing it to buckle in a controlled manner under a specified load.Once buckled,linear springs dominate the response of the system.We demonstrate that this method results in a smaller bias displacement compared to previously reported techniques based on snap-through behaviour,leading to potential reductions in device size and improvements in operational range.The behaviour is analytically modelled and verified through simulations.A prototype device was designed and microfabricated to experimentally validate the design principles.Compared to pre-curved nonlinear springs,the proposed design results in an 11-fold reduction in bias force,a 100-fold reduction in bias displacement,and a reduction in mechanical stiffness by a factor of 520.These results were verified through experiments conducted on a microfabricated accelerometer with an on-chip optical interferometer.Test results reveal an extended linear range of better than 150mg,a bias force of 0.3 mN,and a bias displacement of 10μm,measured with an integrated optical interferometer with a displacement noise floor of 40 pm/√ Hz p at 2 Hz and sensitivity of 194°=mg.
基金provided in part by the Deanship of Scientific Research, King Abdulaziz University, Jeddah, under Grant No. (1-135-36-Hi Ci)
文摘Greenhouse solar-energy driven desalination technology is potentially well suited for supplying water and small scale irrigation in remote and/or rural areas, and for avoiding over-exploitation of available water resources. The efficiency and productivity of these systems are however low, in part because the heat of evaporation has to be transferred as waste heat to ambient air during condensation. In order to maximize energy regeneration during condensation we propose an educator based system that lowers the evaporation process temperature by reducing pressure. The feasibility of the educator assisted passive solar desalination system is investigated using a detailed computational fluid dynamics analysis complemented by experiments. The study focuses in particular on the ability of the new design to lower the required evaporation temperature and thereby reduce the energy intensity of the process. Two configurations, with open and closed educator, are investigated and a detailed analysis of the thermofluid processes is presented. The configuration with a closed educator installed outside the evaporation chamber shows very promising performance. The proposed system can maintain the maximum temperature and pressure in theevaporation chamber below the desirable temperature and pressure thresholds （30 ℃ and 5 kPa）. The analysis and experimental data also show it is possible to further reduce energy requirements by reducing the motive water flow rates.
基金supported by the National Natural Science Foundation of China (No. 51877136)the Shanghai Committee of Science and Technology (No. 19DZ1205403)the Inner Mongolia Autonomous Region Committee of Science and Technology (No. 2020GG0299)。
文摘The bipolar low-voltage DC(LVDC) distribution system has become a prospective solution to better integration of renewables and improvement of system efficiency and reliability. However, it also faces the challenge of power and voltage imbalance between two poles. To solve this problem, an interface converter with bipolar asymmetrical operating capabilities is applied in this paper. The steady-state models of the bipolar LVDC distribution system equipped with this interface converter in the gridconnected mode and off-grid mode are analyzed. A control scheme based on DC offset injection at the secondary side of the interface converter is proposed, enabling the bipolar LVDC distribution system to realize the unbalanced power transfer between two poles in the grid-connected mode and maintain the inherentpole voltage balance in the off-grid mode. Furthermore, this paper also proposes a primary-side DC offset injection control scheme according to the analysis of the magnetic circuit model, which can eliminate the DC bias flux caused by the secondaryside DC offset. Thereby, the potential core magnetic saturation and overcurrent issues can be prevented, ensuring the safety of the interface converter and distribution system. Detailed simulations based on the proposed control scheme are conducted to validate the function of power and voltage balance under the operation conditions of different DC loads.
基金supported by the Discovery and Discovery Accelerator Supplement Grant 2016-04334funded by the Natural Sciences and Engineering Research Council of Canada (NSERC)。
文摘In this study,based on inspiration drawn from origami and the suction mechanism of leeches,a dry electrode is developed for reliable blood pressure(BP)monitoring.The leech-inspired suction mechanism generated a local soft vacuum facilitating appropriate contact with the human skin.Subsequently,an electrocardiogram(ECG)sensor,termed a leech-inspired origami(LIO)sensor,was constructed using the developed dry electrode.The LIO with a sensing robot system ensures reliable ECG signals with a signal-to-noise ratio of 21.7±0.56 dB.From the paired detection of ECG and photoplethysmography(PPG)through human-robot interaction,BP monitoring was demonstrated.The average difference of the systolic BP between that estimated by the sensing robot and that monitored by the sphygmomanometer was 0.03 mmHg,indicating the reliable BP monitoring ability of the sensing robot.The LIO sensing system inspired by origami and leech behaviors makes BP sensing tools feasible,which in turn would further the development of a remote healthcare monitoring robotic system.
基金supported by the Discovery and Discovery Accelerator Supplement Grant 2016-04334funded by the Natural Sciences and Engineering Research Council of Canada(NSERC).
文摘A pressure monitoring structure is a very useful element for a wearable device for health monitoring and sports biomechanics.While pressure sensors have been studied extensively,battery-free functions working in wireless detection have not been studied much.Here,we report a 3D-structured origami-based architecture sensor for wireless pressure monitoring.We developed an architectured platform for wireless pressure sensing through inductorcapacitor(LC)sensors and a monopole antenna.A personalized smart insole with Miura-ori origami designs has been 3D printed together with conductive 3D printed sensors seamlessly.Wireless monitoring of resonant frequency and intensity changes of LC sensors have been demonstrated to monitor foot pressure for different postures.The sensitivity of the wireless pressure sensor is tunable from 15.7 to 2.1 MHz/kPa in the pressure ranges from 0 to 9 kPa and from 10 to 40 kPa,respectively.The proposed wireless pressure-sensing platform can be utilized for various applications such as orthotics,prosthetics,and sports gear.
基金support from the Natural Sciences and Engineering Research Council of Canada(NSERC)and Hodgson Orthopedic Group.
文摘We present here a 3D-printed pressure mapping mat,equipped with customizable architecture sensors,that offers a cost-effective and adaptable solution,overcoming the size constraints and sensing accuracy issues commonly associated with existing commercial pressure mats across various fields,such as healthcare and sports applications.Leveraging a pillar-origami structure,the demonstrated sensor offers multifaceted stiffness properties,effectively filtering skin deformations and enabling capacitive pressure sensing.Notably,the sensor’s detection range can be finely tuned,spanning from 70 to 2500 kPa,with a sensitivity range between 0.01 kPa^(−1) and 0.0002 kPa^(−1),and an impressive response time of just 800 milliseconds.Furthermore,the inclusion of a modular sensor array enhances maintenance and allows for greater flexibility in shaping and enhancing the device’s resolution.This technology finds practical applications in wireless foot pressure mapping and sports protection pads,marking a significant milestone in the advancement of flexible and custom-shaped pressure sensor technology.
