This paper studies the interface curing stresses between polymethyl methacrylate(PMMA)and composite by means of digital speckle correlation method(DSCM).A new method by combining DSCM with the marker points is develop...This paper studies the interface curing stresses between polymethyl methacrylate(PMMA)and composite by means of digital speckle correlation method(DSCM).A new method by combining DSCM with the marker points is developed to measure the interface curing stresses,and the measurement principle is introduced.The interface curing stresses between PMMA and composite with different curing bonding conditions are measured and analyzed,this indicates that the residual stress for furnace heating and furnace cooling is the smallest.Finally,the measurement error is discussed by means of finite element method,the influences of glass microsphere between adhesive and PMMA can be ignored.展开更多
High spatiotemporal resolution brain electrical signals are critical for basic neuroscience research and high-precision focus diagnostic localization,as the spatial scale of some pathologic signals is at the submillim...High spatiotemporal resolution brain electrical signals are critical for basic neuroscience research and high-precision focus diagnostic localization,as the spatial scale of some pathologic signals is at the submillimeter or micrometer level.This entails connecting hundreds or thousands of electrode wires on a limited surface.This study reported a class of flexible,ultrathin,highdensity electrocorticogram(ECoG)electrode arrays.The challenge of a large number of wiring arrangements was overcome by a laminated structure design and processing technology improvement.The flexible,ultrathin,high-density ECoG electrode array was conformably attached to the cortex for reliable,high spatial resolution electrophysiologic recordings.The minimum spacing between electrodes was 15μm,comparable to the diameter of a single neuron.Eight hundred electrodes were prepared with an electrode density of 4444 mm^(-2).In focal epilepsy surgery,the flexible,high-density,laminated ECoG electrode array with 36 electrodes was applied to collect epileptic spike waves inrabbits,improving the positioning accuracy of epilepsy lesions from the centimeter to the submillimeter level.The flexible,high-density,laminated ECoG electrode array has potential clinical applications in intractable epilepsy and other neurologic diseases requiring high-precision electroencephalogram acquisition.展开更多
Epidermal electronic systems feature physical properties that approximate those of the skin,to enable intimate,long-lived skin interfaces for physiological measurements,human–machine interfaces and other applications...Epidermal electronic systems feature physical properties that approximate those of the skin,to enable intimate,long-lived skin interfaces for physiological measurements,human–machine interfaces and other applications that cannot be addressed by wearable hardware that is commercially available today.A primary challenge is power supply;the physical bulk,large mass and high mechanical modulus associated with conventional battery technologies can hinder efforts to achieve epidermal characteristics,and near-field power transfer schemes offer only a limited operating distance.Here we introduce an epidermal,farfield radio frequency(RF)power harvester built using a modularized collection of ultrathin antennas,rectifiers and voltage doublers.These components,separately fabricated and tested,can be integrated together via methods involving soft contact lamination.Systematic studies of the individual components and the overall performance in various dielectric environments highlight the key operational features of these systems and strategies for their optimization.The results suggest robust capabilities for battery-free RF power,with relevance to many emerging epidermal technologies.展开更多
Precise,quantitative in vivo monitoring of hydration levels in the near surface regions of the skin can be useful in preventing skinbased pathologies,and regulating external appearance.Here we introduce multimodal sen...Precise,quantitative in vivo monitoring of hydration levels in the near surface regions of the skin can be useful in preventing skinbased pathologies,and regulating external appearance.Here we introduce multimodal sensors with important capabilities in this context,rendered in soft,ultrathin,‘skin-like’formats with numerous advantages over alternative technologies,including the ability to establish intimate,conformal contact without applied pressure,and to provide spatiotemporally resolved data on both electrical and thermal transport properties from sensitive regions of the skin.Systematic in vitro studies and computational models establish the underlying measurement principles and associated approaches for determination of temperature,thermal conductivity,thermal diffusivity,volumetric heat capacity,and electrical impedance using simple analysis algorithms.Clinical studies on 20 patients subjected to a variety of external stimuli validate the device operation and allow quantitative comparisons of measurement capabilities to those of existing state-of-the-art tools.展开更多
The rapid development of biomedical en-gineering has laid a solid foundation for integrated healthcare monitoring systems across hospital and ambulatory settings.As a key technology in this field,flexible and wearable...The rapid development of biomedical en-gineering has laid a solid foundation for integrated healthcare monitoring systems across hospital and ambulatory settings.As a key technology in this field,flexible and wearable bio-electronics,with distinct mechanical compliance and bio-compatibility,enable real-time,continuous electrocardiog-raphy(ECG)monitoring,offering new possibilities for early diagnosis and personalized treatment of cardiovascular dis-eases.This review presents a summary of recent advances in flexible and wearable bioelectronics for ECG monitoring from three major perspectives.First,in terms of materials,we highlight the roles of emerging functional materials,such as liquid metals,nanomaterials,and conductive hydrogels,in improving electrical performance and user comfort.Second,for structural design,we discuss strategies including micro-needle arrays,bioinspired geometries,and stretchable inter-connects to enhance skin-electrode interface stability and adaptability to body motion.Third,at the system level,we analyse the integration of multichannel and multimodal sen-sing and wireless transmission technologies to support prac-tical ECG applications.Finally,current challenges,including long-term reliability and data security risks,are discussed,and future directions are proposed,including material–structure co-optimization and AI-assisted analysis,to guide the devel-opment of next-generation intelligent ECG monitoring sys-tems.展开更多
Signal drift and performance instability of brain-computer interface devices induced by the interface failure between rigid metal electrodes and soft human skin hinder the precise data acquisition of electroencephalog...Signal drift and performance instability of brain-computer interface devices induced by the interface failure between rigid metal electrodes and soft human skin hinder the precise data acquisition of electroencephalogram(EEG).Thus,it is desirable to achieve a robust interface for brain-computer interface devices.Here,a kind of polydopamine methacrylamide-polyacrylamide(PDMA-PAAM)hydrogel is developed.To improve the adhesion,dopamine is introduced into the polyacrylamide hydrogel,through the amino and catechol groups of dopamine in an organic-inorganic interface to build a covalent and non-covalent interaction.A strong attachment and an effective modulus transition system can be formed between the metal electrodes and human skin,so that the peeling force between the PDMAPAAM hydrogel and the porcine skin can reach 22 N m^(-1).In addition,the stable conductivity and long-term operating life of the PDMA-PAAM hydrogel for more than 60 days at room temperature are achieved by adding sodium chloride(NaCl)and glycerol,respectively.The PDMA-PAAM hydrogel membrane fabricated in this work is integrated onto a flexible Au electrode applied in a brain-computer interface.In comparison,the collected EEG signal intensity and waveform are consistent with that of the commercial counterparts.And obviously,the flexible electrode with PDMA-PAAM hydrogel membrane is demonstrated to enable a more stable and userfriendly interface.展开更多
Electromyography(EMG)signal is the electrical potential generated by contracting muscle cells.Long-term and accurate EMG monitoring is desirable for neuromuscular function assessment in clinical and the human–compute...Electromyography(EMG)signal is the electrical potential generated by contracting muscle cells.Long-term and accurate EMG monitoring is desirable for neuromuscular function assessment in clinical and the human–computer interfaces.Herein,we report a skin-integrated,biocompatible,and stretchable silicon microneedle electrode(SSME)inspired by the plant thorns.The silicon microneedles are half encapsulated by the polyimide(PI)to enhance the adaptability to deformation and resistance to fatigue.Thorn-like SSME is realized by the semi-additive method with a stretchability of not less than 36%.The biocompatibility of SSME has been verified using cytotoxicity tests.EMG monitoring in motion and long-term has been conducted to demonstrate the feasibility and performance of the SSME,which is compared with a commercial wet electrode.Hopefully,the strategies reported here can lead to accurate and long-term EMG monitoring,facilitating an effective and reliable human–computer interface.展开更多
Twenty-four hours continuous intraocular pressure(IOP)monitoring is beneficial for glaucoma care.Contact lens sensors using LC technology can achieve non-invasive continuous IOP measuring around the clock and are rela...Twenty-four hours continuous intraocular pressure(IOP)monitoring is beneficial for glaucoma care.Contact lens sensors using LC technology can achieve non-invasive continuous IOP measuring around the clock and are relatively simple in principle and structure,thus dominating the mainstream.Among them,stretchable inductive LC contact lens sensors constructed with liquid metal have advantages in signal quality as well as wearing comfort,but currently its sensitivity is slightly insufficient.Here,we propose an LC sensor that constructed with liquid metal to form the stretchable inductance and capacitance further.The capacitive plate and inductive coil can response to IOP changes simultaneously,thus able to enhance the sensitivity in principle.We modeled the sensing mechanism and conducted design,fabrication,as well as various tests.The device exhibits good characteristics,including reliability,good signal quality,etc.Especially,it has a threefold increase in sensitivity,exceeding the current state-of-the-art contact lens sensors.展开更多
基金supported by the National Basic Research Program (973 Program) of China (2011CB606105)
文摘This paper studies the interface curing stresses between polymethyl methacrylate(PMMA)and composite by means of digital speckle correlation method(DSCM).A new method by combining DSCM with the marker points is developed to measure the interface curing stresses,and the measurement principle is introduced.The interface curing stresses between PMMA and composite with different curing bonding conditions are measured and analyzed,this indicates that the residual stress for furnace heating and furnace cooling is the smallest.Finally,the measurement error is discussed by means of finite element method,the influences of glass microsphere between adhesive and PMMA can be ignored.
基金support of the National Natural Science Foundation of China(Nos.U20A6001,12002190,11972207,and 11921002)the Fundamental Research Funds for the Central Universities,China(No.SWUKQ22029)the Chongqing Natural Science Foundation of China(No.CSTB2022NSCQ-MSX1635).
文摘High spatiotemporal resolution brain electrical signals are critical for basic neuroscience research and high-precision focus diagnostic localization,as the spatial scale of some pathologic signals is at the submillimeter or micrometer level.This entails connecting hundreds or thousands of electrode wires on a limited surface.This study reported a class of flexible,ultrathin,highdensity electrocorticogram(ECoG)electrode arrays.The challenge of a large number of wiring arrangements was overcome by a laminated structure design and processing technology improvement.The flexible,ultrathin,high-density ECoG electrode array was conformably attached to the cortex for reliable,high spatial resolution electrophysiologic recordings.The minimum spacing between electrodes was 15μm,comparable to the diameter of a single neuron.Eight hundred electrodes were prepared with an electrode density of 4444 mm^(-2).In focal epilepsy surgery,the flexible,high-density,laminated ECoG electrode array with 36 electrodes was applied to collect epileptic spike waves inrabbits,improving the positioning accuracy of epilepsy lesions from the centimeter to the submillimeter level.The flexible,high-density,laminated ECoG electrode array has potential clinical applications in intractable epilepsy and other neurologic diseases requiring high-precision electroencephalogram acquisition.
基金XF and YM acknowledge the support from the National Basic Research Program of China(Grant No.2015CB351900)the National Natural Science Foundation of China(Grant Nos.11402135 and 11320101001).
文摘Epidermal electronic systems feature physical properties that approximate those of the skin,to enable intimate,long-lived skin interfaces for physiological measurements,human–machine interfaces and other applications that cannot be addressed by wearable hardware that is commercially available today.A primary challenge is power supply;the physical bulk,large mass and high mechanical modulus associated with conventional battery technologies can hinder efforts to achieve epidermal characteristics,and near-field power transfer schemes offer only a limited operating distance.Here we introduce an epidermal,farfield radio frequency(RF)power harvester built using a modularized collection of ultrathin antennas,rectifiers and voltage doublers.These components,separately fabricated and tested,can be integrated together via methods involving soft contact lamination.Systematic studies of the individual components and the overall performance in various dielectric environments highlight the key operational features of these systems and strategies for their optimization.The results suggest robust capabilities for battery-free RF power,with relevance to many emerging epidermal technologies.
基金YM and XF acknowledge the support from the National Basic Research Program of China(Grant No.2015CB351900)National Natural Science Foundation of China(Grant Nos.11402135,11320101001)+2 种基金YH acknowledges the support from NSF(Grant Nos.DMR1121262,CMMI1300846,CMMI1400169,and CMMI1534120)the NIH(Grant No.R01EB019337)RCW acknowledges support from the National Science Foundation under grant no.DGE-1144245.
文摘Precise,quantitative in vivo monitoring of hydration levels in the near surface regions of the skin can be useful in preventing skinbased pathologies,and regulating external appearance.Here we introduce multimodal sensors with important capabilities in this context,rendered in soft,ultrathin,‘skin-like’formats with numerous advantages over alternative technologies,including the ability to establish intimate,conformal contact without applied pressure,and to provide spatiotemporally resolved data on both electrical and thermal transport properties from sensitive regions of the skin.Systematic in vitro studies and computational models establish the underlying measurement principles and associated approaches for determination of temperature,thermal conductivity,thermal diffusivity,volumetric heat capacity,and electrical impedance using simple analysis algorithms.Clinical studies on 20 patients subjected to a variety of external stimuli validate the device operation and allow quantitative comparisons of measurement capabilities to those of existing state-of-the-art tools.
基金supported by the Innovation Training Fund of the Sixth Medical Center,Chinese PLA General Hospital (CXPY202318)。
文摘The rapid development of biomedical en-gineering has laid a solid foundation for integrated healthcare monitoring systems across hospital and ambulatory settings.As a key technology in this field,flexible and wearable bio-electronics,with distinct mechanical compliance and bio-compatibility,enable real-time,continuous electrocardiog-raphy(ECG)monitoring,offering new possibilities for early diagnosis and personalized treatment of cardiovascular dis-eases.This review presents a summary of recent advances in flexible and wearable bioelectronics for ECG monitoring from three major perspectives.First,in terms of materials,we highlight the roles of emerging functional materials,such as liquid metals,nanomaterials,and conductive hydrogels,in improving electrical performance and user comfort.Second,for structural design,we discuss strategies including micro-needle arrays,bioinspired geometries,and stretchable inter-connects to enhance skin-electrode interface stability and adaptability to body motion.Third,at the system level,we analyse the integration of multichannel and multimodal sen-sing and wireless transmission technologies to support prac-tical ECG applications.Finally,current challenges,including long-term reliability and data security risks,are discussed,and future directions are proposed,including material–structure co-optimization and AI-assisted analysis,to guide the devel-opment of next-generation intelligent ECG monitoring sys-tems.
基金supported by the National Natural Science Foundation of China(U20A6001,11921002,and 11902292)Zhejiang Province Key Research and Development Project(2021C01183,2020C05004,and 2021C05007-4)the Natural Science Foundation of Zhejiang Province of China(LQ19E030003)。
文摘Signal drift and performance instability of brain-computer interface devices induced by the interface failure between rigid metal electrodes and soft human skin hinder the precise data acquisition of electroencephalogram(EEG).Thus,it is desirable to achieve a robust interface for brain-computer interface devices.Here,a kind of polydopamine methacrylamide-polyacrylamide(PDMA-PAAM)hydrogel is developed.To improve the adhesion,dopamine is introduced into the polyacrylamide hydrogel,through the amino and catechol groups of dopamine in an organic-inorganic interface to build a covalent and non-covalent interaction.A strong attachment and an effective modulus transition system can be formed between the metal electrodes and human skin,so that the peeling force between the PDMAPAAM hydrogel and the porcine skin can reach 22 N m^(-1).In addition,the stable conductivity and long-term operating life of the PDMA-PAAM hydrogel for more than 60 days at room temperature are achieved by adding sodium chloride(NaCl)and glycerol,respectively.The PDMA-PAAM hydrogel membrane fabricated in this work is integrated onto a flexible Au electrode applied in a brain-computer interface.In comparison,the collected EEG signal intensity and waveform are consistent with that of the commercial counterparts.And obviously,the flexible electrode with PDMA-PAAM hydrogel membrane is demonstrated to enable a more stable and userfriendly interface.
基金the financial support from the National Natural Science Foundation of China(Grant No.U20A6001,11902292)Zhejiang Province Key Research and Development Project(Grant No.2021C01183,2021C05007-4).
文摘Electromyography(EMG)signal is the electrical potential generated by contracting muscle cells.Long-term and accurate EMG monitoring is desirable for neuromuscular function assessment in clinical and the human–computer interfaces.Herein,we report a skin-integrated,biocompatible,and stretchable silicon microneedle electrode(SSME)inspired by the plant thorns.The silicon microneedles are half encapsulated by the polyimide(PI)to enhance the adaptability to deformation and resistance to fatigue.Thorn-like SSME is realized by the semi-additive method with a stretchability of not less than 36%.The biocompatibility of SSME has been verified using cytotoxicity tests.EMG monitoring in motion and long-term has been conducted to demonstrate the feasibility and performance of the SSME,which is compared with a commercial wet electrode.Hopefully,the strategies reported here can lead to accurate and long-term EMG monitoring,facilitating an effective and reliable human–computer interface.
基金the support from the National Basic Research Program of China(Grant No.2023YFB3609002)the National Natural Science Foundation of China(Grant Nos.12225209 and U21A20502)+2 种基金the Tsinghua Precision Medicine Foundation(Grant No.100010104)the capital health research and development of special(Grant No.2022-4-4019)the Natural Science Foundation of Zhejiang Province(Grant No.LQ23H18007).
文摘Twenty-four hours continuous intraocular pressure(IOP)monitoring is beneficial for glaucoma care.Contact lens sensors using LC technology can achieve non-invasive continuous IOP measuring around the clock and are relatively simple in principle and structure,thus dominating the mainstream.Among them,stretchable inductive LC contact lens sensors constructed with liquid metal have advantages in signal quality as well as wearing comfort,but currently its sensitivity is slightly insufficient.Here,we propose an LC sensor that constructed with liquid metal to form the stretchable inductance and capacitance further.The capacitive plate and inductive coil can response to IOP changes simultaneously,thus able to enhance the sensitivity in principle.We modeled the sensing mechanism and conducted design,fabrication,as well as various tests.The device exhibits good characteristics,including reliability,good signal quality,etc.Especially,it has a threefold increase in sensitivity,exceeding the current state-of-the-art contact lens sensors.
