In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance ...In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.展开更多
The development of intelligent electronic power systems necessitates advanced flexible pressure sensors.Despite improved compressibility through surface micro-structures or bulk pores,conventional capacitive pressure ...The development of intelligent electronic power systems necessitates advanced flexible pressure sensors.Despite improved compressibility through surface micro-structures or bulk pores,conventional capacitive pressure sensors face limitations due to their low dielectric constant and poor temperature tolerance of most elastomers.Herein,we constructed oriented polyimide-based aerogels with mechanical robustness and notable changes in dielectric constant under compression.The enhancement is attributed to the doping of surface-modified dielectric nanoparticles and graphene oxide sheets,which interact with polymer molecular chains.The resulting aerogels,with their excellent temperature resistance,were used to assemble high-performance capacitive pressure sensors.The sensor exhibits a maximum sensitivity of 1.41 kPa^(−1)over a wide working range of 0-200 kPa.Meanwhile,the sensor can operate in environments up to 150℃during 2000 compression/release cycles.Furthermore,the aerogel-based sensor demonstrates proximity sensing capabilities,showing great potential for applications in non-contact sensing and extreme environment detection.展开更多
In this paper, first a circular diaphragm is modeled using the classical plate theory. An analytical solution based on differential transformation method （DTM） and Runge-Kutta method is employed for solving the gove...In this paper, first a circular diaphragm is modeled using the classical plate theory. An analytical solution based on differential transformation method （DTM） and Runge-Kutta method is employed for solving the governing differential equation for the first time. Then the influences of various parameters on central deflection of the diaphragm, stress distribution and capacitance of pressure sensor with a time-dependent pressure are examined. Several case studies are compared with simulations to confirm the proposed method. The analytical results compared with ABAQUS simulation show excellent agreement with the simulation results. This method is very promising for time saving in calculating micro-device characteristics.展开更多
Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stab...Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stability have hindered their large-scale commercial application.Herein,aflexible capacitive pressure sensor based on an interdigital electrode structure with two porous microneedle arrays(MNAs)is pro-posed.The porous substrate that constitutes the MNA is a mixed product of polydimethylsiloxane and NaHCO3.Due to its porous and interdigital structure,the maximum sensitivity(0.07 kPa-1)of a porous MNA-based pressure sensor was found to be seven times higher than that of an imporous MNA pressure sensor,and it was much greater than that of aflat pressure sensor without a porous MNA structure.Finite-element analysis showed that the interdigital MNA structure can greatly increase the strain and improve the sensitivity of the sen-sor.In addition,the porous MNA-based pressure sensor was found to have good stability over 1500 loading cycles as a result of its bilayer parylene-enhanced conductive electrode structure.Most importantly,it was found that the sensor could accurately monitor the motion of afinger,wrist joint,arm,face,abdomen,eye,and Adam’s apple.Furthermore,preliminary semantic recognition was achieved by monitoring the movement of the Adam’s apple.Finally,multiple pressure sensors were integrated into a 33 array to detect a spatial pressure distribu-×tion.Compared to the sensors reported in previous works,the interdigital electrode structure presented in this work improves sensitivity and stability by modifying the electrode layer rather than the dielectric layer.展开更多
Electronic skin(e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin(e-skin) into true ¨skin¨is the ultimate goal. Tactile sensin...Electronic skin(e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin(e-skin) into true ¨skin¨is the ultimate goal. Tactile sensing is a fundamental function of skin and the development of high-performance flexible pressure sensors is necessary to realize thus. Many reports on flexible pressure sensors have been published in recent years,including numerous studies on improving sensor performance, and in particular, sensitivity. In addition,a number of studies have investigated self-healing materials, multifunctional sensing, and so on. Here,we review recent developments in flexible pressure sensors. First, working principles of flexible pressure sensors, including piezoresistivity, capacitance, and piezoelectricity, are introduced, as well as working mechanisms such as triboelectricity. Then studies on improving the performance of piezoresistive and capacitive flexible pressure sensors are discussed, in addition to other important aspects of this intriguing research field. Finally, we summarize future challenges in developing novel flexible pressure sensors.展开更多
The development of pressure sensors with highly sensitivity, fast response and facile fabrication technique is desirable for wearable electronics. Here, we successfully fabricated a flexible transparent capacitive pre...The development of pressure sensors with highly sensitivity, fast response and facile fabrication technique is desirable for wearable electronics. Here, we successfully fabricated a flexible transparent capacitive pressure sensor based on patterned microstructured silver nanowires(AgNWs)/polydimethylsiloxane(PDMS) composite dielectrics. Compared with the pure PDMS dielectric layer with planar structures, the patterned microstructured sensor exhibits a higher sensitivity(0.831 kPa^-1, <0.5 kPa), a lower detection limit,good stability and durability. The enhanced sensing mechanism about the conductive filler content and the patterned microstructures has also been discussed. A 5×5 sensor array was then fabricated to be used as flexible and transparent wearable touch keyboards systems. The fabricated pressure sensor has great potential in the future electronic skin area.展开更多
The design of a maskless exposure system for fabricating the microstructured surface based on the grainy light illumination generated by laser speckle is reported. Upon combining with soft lithography, we obtained mic...The design of a maskless exposure system for fabricating the microstructured surface based on the grainy light illumination generated by laser speckle is reported. Upon combining with soft lithography, we obtained microstructured polydimethylsiloxane electrodes with microstructure sizes of 20 μm and 40 μm and microstructure fill factors ranging from 10% to 90%. The feasibility of using this method in fabricating high-sensitivity capacitive pressure sensors was demonstrated. The sensor shows the highest sensitivity of 2.14 k Pa-1under 0–100 Pa pressures, the low detection limit of 4.9 Pa, and the excellent stability and durability of 10000 cycles. The method of employing laser speckle in fabricating microstructures with different morphologies is simple and robust, which is superior to other methods such as traditional photolithography.展开更多
Achieving a high sensitivity for practical applications has always been one of the main developmental directions for wearable flexible pressure sensors.This paper introduces a laser speckle grayscale lithography syste...Achieving a high sensitivity for practical applications has always been one of the main developmental directions for wearable flexible pressure sensors.This paper introduces a laser speckle grayscale lithography system and a novel method for fabricating random conical array microstructures using grainy laser speckle patterns.Its feasibility is attributed to the autocorrelation function of the laser speckle intensity,which adheres to a first-order Bessel function of the first kind.Through objective speckle size and exposure dose manipulations,we developed a microstructured photoresist with various micromorphologies.These microstructures were used to form polydimethylsiloxane microstructured electrodes that were used in flexible capacitive pressure sensors.These-1 sensors exhibited an ultra-high sensitivity:19.76 kPa for the low-pressure range of 0-100 Pa.Their minimum detection threshold was 1.9 Pa,and they maintained stability and resilience over 10,000 test cycles.These sensors proved to be adept at capturing physiological signals and providing tactile feedback,thereby emphasizing their practical value.展开更多
Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide ap...Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide applications owing to the high cost or low accuracy.In this study,a flexible sitting pressure measurement system was proposed based on a textile-based capacitive pressure sensor array in order to measure sitting pressure distribution simply and conveniently.The capacitive pressure sensor array is sandwich structure composed of a high-density sponge layer and two electrode array fabrics,which possesses high resolution(2.26 sensors/cm^(2)),high sensitivity(0.701 kPa^(-1))and fast response(≤35 ms).It is worth noting that the raw materials of the sensing fabric include commercialized copper sheets and polyester yarns.The as-prepared pressure measurement system can accurately measure the pressure distribution nephogram for sitting posture analysis.The sitting pressure of 10 volunteers was measured and six types of posture were distinguished clearly.展开更多
Bio-inspired near-sensor computing,which integrates sensing and processing functions,presents a promising strategy to enhance efficiency and reduce latency in such applications.Here,we introduce tactile sensory nerve ...Bio-inspired near-sensor computing,which integrates sensing and processing functions,presents a promising strategy to enhance efficiency and reduce latency in such applications.Here,we introduce tactile sensory nerve systems with biologically realistic energy efficiency,utilizing starfish-inspired capacitive pressure sensors integrated with flexible memristors.These starfish-inspired sensors,with their high aspect ratio(~3)and stress-focusing,hourglass-shaped dielectric microstructures,enable highly sensitive tactile detection across a broad pressure range,effectively mimicking the properties of human skin.Artificial tactile sensory nerves,which integrate the capacitive sensor with a flexible memristor exhibiting synaptic plasticity,function reliably as energy-efficient near-sensor computing systems by bio-realistically transducing mechanical stimuli into transient electrical signals.The developed system operates as both an artificial nociceptor and a tactile near-sensor computing unit,with energy consumption approaching biological levels at approximately 140 pJ and 2.2 fJ,respectively.This neuro-inspired localized computing strategy offers a physical platform for advanced smart user interface applications.展开更多
Transient electronics,comprising of degradable devices that disintegrate and disappear after their operational life,has received considerable interest in recent years because of the concerns related to the rapidly gro...Transient electronics,comprising of degradable devices that disintegrate and disappear after their operational life,has received considerable interest in recent years because of the concerns related to the rapidly growing electronic waste(e-waste).However,the degradability or biodegradability of electronic devices alone is insufficient to ascertain environmental safety.The evaluation of the nature of degradation by-products is also essential to assess the environmental impact of a degradable device.Herein,we investigate systematically the hydrolytic degradation by-products of two different types of devices viz.a capacitive pressure sensor and a photodetector,using liquid chromatograph mass spectrometry.The findings reveal that,despite the inherent degradability of constituent materials used in an electronic device,the released by-products can be toxic or could be complex molecules with unknown chemistry such as carcinogenic or contain almost non-degradable polystyrene derivatives/microplastic(e.g.,from PEDOT:PSS),or have copper complexes resulting from degraded silk fibroin and poly(ethylene oxide)mass fragments.This analysis underlines the need for careful selection and reassessment of materials employed in transient electronics,as an important factor,to mitigate the end-of-life issues associated with electronics and its environmental impact.展开更多
Silicone foams with and without liquid fillers(silicone oils of various types and glycerol,respectively)are synthesized and analyzed to be used as dielectric layers in capacitive sensors.A simple fabrication technique...Silicone foams with and without liquid fillers(silicone oils of various types and glycerol,respectively)are synthesized and analyzed to be used as dielectric layers in capacitive sensors.A simple fabrication technique involving only four components i.e.Sylgard 184,glycerol,sodium hydroxide and ethanol is used to make these silicone foams after which they are filled with silicone oil or glycerol by soaking the foam in respective liquid.Mechanical and dielectric properties of the foams are examined.The oil reinforces the foam’s dielectric properties,softens the foam and improves its capacitive response,making it a very good dielectric material for fabricating capacitive pressure sensors.Compared to dry silicone foams,foams filled with-and swollen by-chloropropyl-functional silicone oil,show a low Young’smodulus(31 kPa),a high and stable relative dielectric permittivity of around 5,and a high capacitive response of 132%for an appliedpressureof 12 kPa.Thepresence of oil stabilizes the soft foam and ensures that it does not buckle under high pressure.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12272369)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0620101).
文摘In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.
基金financially supported by the National Key Research&Development Program of China(No.2022YFA1205200).
文摘The development of intelligent electronic power systems necessitates advanced flexible pressure sensors.Despite improved compressibility through surface micro-structures or bulk pores,conventional capacitive pressure sensors face limitations due to their low dielectric constant and poor temperature tolerance of most elastomers.Herein,we constructed oriented polyimide-based aerogels with mechanical robustness and notable changes in dielectric constant under compression.The enhancement is attributed to the doping of surface-modified dielectric nanoparticles and graphene oxide sheets,which interact with polymer molecular chains.The resulting aerogels,with their excellent temperature resistance,were used to assemble high-performance capacitive pressure sensors.The sensor exhibits a maximum sensitivity of 1.41 kPa^(−1)over a wide working range of 0-200 kPa.Meanwhile,the sensor can operate in environments up to 150℃during 2000 compression/release cycles.Furthermore,the aerogel-based sensor demonstrates proximity sensing capabilities,showing great potential for applications in non-contact sensing and extreme environment detection.
文摘In this paper, first a circular diaphragm is modeled using the classical plate theory. An analytical solution based on differential transformation method （DTM） and Runge-Kutta method is employed for solving the governing differential equation for the first time. Then the influences of various parameters on central deflection of the diaphragm, stress distribution and capacitance of pressure sensor with a time-dependent pressure are examined. Several case studies are compared with simulations to confirm the proposed method. The analytical results compared with ABAQUS simulation show excellent agreement with the simulation results. This method is very promising for time saving in calculating micro-device characteristics.
基金supported in part by the National Natural Science Foundation of China(Grant No.62104056)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ21F010010)+4 种基金the National Natural Science Foundation of China(Grant Nos.62141409 and 62204204)the National Key R&D Program of China(Grant No.2022ZD0208602)the Zhejiang Provincial Key Research&Development Fund(Grant Nos.2019C04003 and 2021C01041)the Shanghai Sailing Program(Grant No.21YF1451000)the Key Research and Development Program of Shaanxi(Grant No.2022GY-001).
文摘Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stability have hindered their large-scale commercial application.Herein,aflexible capacitive pressure sensor based on an interdigital electrode structure with two porous microneedle arrays(MNAs)is pro-posed.The porous substrate that constitutes the MNA is a mixed product of polydimethylsiloxane and NaHCO3.Due to its porous and interdigital structure,the maximum sensitivity(0.07 kPa-1)of a porous MNA-based pressure sensor was found to be seven times higher than that of an imporous MNA pressure sensor,and it was much greater than that of aflat pressure sensor without a porous MNA structure.Finite-element analysis showed that the interdigital MNA structure can greatly increase the strain and improve the sensitivity of the sen-sor.In addition,the porous MNA-based pressure sensor was found to have good stability over 1500 loading cycles as a result of its bilayer parylene-enhanced conductive electrode structure.Most importantly,it was found that the sensor could accurately monitor the motion of afinger,wrist joint,arm,face,abdomen,eye,and Adam’s apple.Furthermore,preliminary semantic recognition was achieved by monitoring the movement of the Adam’s apple.Finally,multiple pressure sensors were integrated into a 33 array to detect a spatial pressure distribu-×tion.Compared to the sensors reported in previous works,the interdigital electrode structure presented in this work improves sensitivity and stability by modifying the electrode layer rather than the dielectric layer.
基金supported by the National Natural Science Foundation of China(Nos.61775032,61475134 and 11604042)the Fundamental Research Funds for the Central Universities(N170405007,N180406002,N180408018 and N160404009)the 111 Project(B16009)。
文摘Electronic skin(e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin(e-skin) into true ¨skin¨is the ultimate goal. Tactile sensing is a fundamental function of skin and the development of high-performance flexible pressure sensors is necessary to realize thus. Many reports on flexible pressure sensors have been published in recent years,including numerous studies on improving sensor performance, and in particular, sensitivity. In addition,a number of studies have investigated self-healing materials, multifunctional sensing, and so on. Here,we review recent developments in flexible pressure sensors. First, working principles of flexible pressure sensors, including piezoresistivity, capacitance, and piezoelectricity, are introduced, as well as working mechanisms such as triboelectricity. Then studies on improving the performance of piezoresistive and capacitive flexible pressure sensors are discussed, in addition to other important aspects of this intriguing research field. Finally, we summarize future challenges in developing novel flexible pressure sensors.
基金supported by the National Natural Science Foundation for Distinguished Young Scholars of China(NSFC,61625404)the Key Research Program of Frontier Sciences,CAS(QYZDY-SSW-JWC004)the NSFC(61504136)
文摘The development of pressure sensors with highly sensitivity, fast response and facile fabrication technique is desirable for wearable electronics. Here, we successfully fabricated a flexible transparent capacitive pressure sensor based on patterned microstructured silver nanowires(AgNWs)/polydimethylsiloxane(PDMS) composite dielectrics. Compared with the pure PDMS dielectric layer with planar structures, the patterned microstructured sensor exhibits a higher sensitivity(0.831 kPa^-1, <0.5 kPa), a lower detection limit,good stability and durability. The enhanced sensing mechanism about the conductive filler content and the patterned microstructures has also been discussed. A 5×5 sensor array was then fabricated to be used as flexible and transparent wearable touch keyboards systems. The fabricated pressure sensor has great potential in the future electronic skin area.
基金supported by the National Key Research and Development Program of China (Grant No. 2017YFA0304203)the Key Research and Development Program of Shanxi Province (Grant No. 202102030201002)+3 种基金the Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (Grant No. IRT_17R70)the State Key Program of National Natural Science of China (Grant No. 11434007)the111 Project (Grant No. D18001)the Fund for Shanxi “1331 Project”。
文摘The design of a maskless exposure system for fabricating the microstructured surface based on the grainy light illumination generated by laser speckle is reported. Upon combining with soft lithography, we obtained microstructured polydimethylsiloxane electrodes with microstructure sizes of 20 μm and 40 μm and microstructure fill factors ranging from 10% to 90%. The feasibility of using this method in fabricating high-sensitivity capacitive pressure sensors was demonstrated. The sensor shows the highest sensitivity of 2.14 k Pa-1under 0–100 Pa pressures, the low detection limit of 4.9 Pa, and the excellent stability and durability of 10000 cycles. The method of employing laser speckle in fabricating microstructures with different morphologies is simple and robust, which is superior to other methods such as traditional photolithography.
基金supported by the Key Research and Development Program of Shanxi Province(202102030201002)the Changjiang Scholars and Innovative Research Team at the University of Ministry of Education of China(IRT_17R70)+2 种基金the State Key Program of National Natural Science of China(11434007)the 111 Project(D18001)the Fund for Shanxi“1331 Project”Key Subjects Construction.
文摘Achieving a high sensitivity for practical applications has always been one of the main developmental directions for wearable flexible pressure sensors.This paper introduces a laser speckle grayscale lithography system and a novel method for fabricating random conical array microstructures using grainy laser speckle patterns.Its feasibility is attributed to the autocorrelation function of the laser speckle intensity,which adheres to a first-order Bessel function of the first kind.Through objective speckle size and exposure dose manipulations,we developed a microstructured photoresist with various micromorphologies.These microstructures were used to form polydimethylsiloxane microstructured electrodes that were used in flexible capacitive pressure sensors.These-1 sensors exhibited an ultra-high sensitivity:19.76 kPa for the low-pressure range of 0-100 Pa.Their minimum detection threshold was 1.9 Pa,and they maintained stability and resilience over 10,000 test cycles.These sensors proved to be adept at capturing physiological signals and providing tactile feedback,thereby emphasizing their practical value.
基金Fundamental Research Fund for the Central Universities,China(Nos.2232020G-01 and 19D110106)Young Elite Scientists Sponsorship Program by China Association for Science and Technology,China(No.2017QNRC001)Graduate Student Innovation Fund of Donghua University,China(No.20D310111)。
文摘Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide applications owing to the high cost or low accuracy.In this study,a flexible sitting pressure measurement system was proposed based on a textile-based capacitive pressure sensor array in order to measure sitting pressure distribution simply and conveniently.The capacitive pressure sensor array is sandwich structure composed of a high-density sponge layer and two electrode array fabrics,which possesses high resolution(2.26 sensors/cm^(2)),high sensitivity(0.701 kPa^(-1))and fast response(≤35 ms).It is worth noting that the raw materials of the sensing fabric include commercialized copper sheets and polyester yarns.The as-prepared pressure measurement system can accurately measure the pressure distribution nephogram for sitting posture analysis.The sitting pressure of 10 volunteers was measured and six types of posture were distinguished clearly.
基金supported by the National R&D Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Science and ICT(No.RS-2023-00277635)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2024-00411764)+1 种基金supported by a grant of the Basic Research Program funded by the Korea Institute of Machinery and Materials(grant number:NK254H)the Technology Innovation Program(RS-2024-00443121)funded By the Ministry of Trade Industry&Energy(MOTIE,Korea).
文摘Bio-inspired near-sensor computing,which integrates sensing and processing functions,presents a promising strategy to enhance efficiency and reduce latency in such applications.Here,we introduce tactile sensory nerve systems with biologically realistic energy efficiency,utilizing starfish-inspired capacitive pressure sensors integrated with flexible memristors.These starfish-inspired sensors,with their high aspect ratio(~3)and stress-focusing,hourglass-shaped dielectric microstructures,enable highly sensitive tactile detection across a broad pressure range,effectively mimicking the properties of human skin.Artificial tactile sensory nerves,which integrate the capacitive sensor with a flexible memristor exhibiting synaptic plasticity,function reliably as energy-efficient near-sensor computing systems by bio-realistically transducing mechanical stimuli into transient electrical signals.The developed system operates as both an artificial nociceptor and a tactile near-sensor computing unit,with energy consumption approaching biological levels at approximately 140 pJ and 2.2 fJ,respectively.This neuro-inspired localized computing strategy offers a physical platform for advanced smart user interface applications.
文摘Transient electronics,comprising of degradable devices that disintegrate and disappear after their operational life,has received considerable interest in recent years because of the concerns related to the rapidly growing electronic waste(e-waste).However,the degradability or biodegradability of electronic devices alone is insufficient to ascertain environmental safety.The evaluation of the nature of degradation by-products is also essential to assess the environmental impact of a degradable device.Herein,we investigate systematically the hydrolytic degradation by-products of two different types of devices viz.a capacitive pressure sensor and a photodetector,using liquid chromatograph mass spectrometry.The findings reveal that,despite the inherent degradability of constituent materials used in an electronic device,the released by-products can be toxic or could be complex molecules with unknown chemistry such as carcinogenic or contain almost non-degradable polystyrene derivatives/microplastic(e.g.,from PEDOT:PSS),or have copper complexes resulting from degraded silk fibroin and poly(ethylene oxide)mass fragments.This analysis underlines the need for careful selection and reassessment of materials employed in transient electronics,as an important factor,to mitigate the end-of-life issues associated with electronics and its environmental impact.
基金supported by the China Scholarship CouncilTeknologi og Produktion,Det Frie Forskningsrad。
文摘Silicone foams with and without liquid fillers(silicone oils of various types and glycerol,respectively)are synthesized and analyzed to be used as dielectric layers in capacitive sensors.A simple fabrication technique involving only four components i.e.Sylgard 184,glycerol,sodium hydroxide and ethanol is used to make these silicone foams after which they are filled with silicone oil or glycerol by soaking the foam in respective liquid.Mechanical and dielectric properties of the foams are examined.The oil reinforces the foam’s dielectric properties,softens the foam and improves its capacitive response,making it a very good dielectric material for fabricating capacitive pressure sensors.Compared to dry silicone foams,foams filled with-and swollen by-chloropropyl-functional silicone oil,show a low Young’smodulus(31 kPa),a high and stable relative dielectric permittivity of around 5,and a high capacitive response of 132%for an appliedpressureof 12 kPa.Thepresence of oil stabilizes the soft foam and ensures that it does not buckle under high pressure.
