Neuromorphic vision sensors have been extremely beneficial in developing energy-efficient intelligent systems for robotics and privacy-preserving security applications.There is a dire need for devices to mimic the ret...Neuromorphic vision sensors have been extremely beneficial in developing energy-efficient intelligent systems for robotics and privacy-preserving security applications.There is a dire need for devices to mimic the retina's photoreceptors that encode the light illumination into a sequence of spikes to develop such sensors.Herein,we develop a hybrid perovskite-based flexible photoreceptor whose capacitance changes proportionally to the light intensity mimicking the retina's rod cells,paving the way for developing an efficient artificial retina network.The proposed device constitutes a hybrid nanocomposite of perovskites(methyl-ammonium lead bromide)and the ferroelectric terpolymer(polyvinylidene fluoride trifluoroethylene-chlorofluoroethylene).A metal-insulator-metal type capacitor with the prepared composite exhibits the unique and photosensitive capacitive behavior at various light intensities in the visible light spectrum.The proposed photoreceptor mimics the spectral sensitivity curve of human photopic vision.The hybrid nanocomposite is stable in ambient air for 129 weeks,with no observable degradation of the composite due to the encapsulation of hybrid perovskites in the hydrophobic polymer.The functionality of the proposed photoreceptor to recognize handwritten digits(MNIST)dataset using an unsupervised trained spiking neural network with 72.05%recognition accuracy is demonstrated.This demonstration proves the potential of the proposed sensor for neuromorphic vision applications.展开更多
Inexpensive and easy-to-use diagnostic tools for fast health screening are imperative,especially in the developing world,where portability and affordability are a necessity.Accurate monitoring of metabolite levels can...Inexpensive and easy-to-use diagnostic tools for fast health screening are imperative,especially in the developing world,where portability and affordability are a necessity.Accurate monitoring of metabolite levels can provide useful information regarding key metabolic activities of the body and detect the concomitant irregularities such as in the case of diabetes,a worldwide chronic disease.Today,the majority of daily glucose monitoring tools rely on piercing the skin to draw blood.The pain and discomfort associated with finger pricking have created a global need to develop non-invasive,portable glucose assays.In this work,we develop a disposable analytical device which can measure physiologically relevant glucose concentrations in human saliva based on enzymatic electrochemical detection.We use inkjet-printing technology for the rapid and low-cost deposition of all the components of this glucose sensor,from the electronics to the biorecognition elements,on commercially available paper substrates.The only electronic component of the sensor is the conducting polymer poly(3,4 ethylenedioxythiophene)doped with polystyrene sulfonate(PEDOT:PSS),while the biorecognition element comprises of the enzyme glucose oxidase coupled with an electron mediator.We demonstrate that one month after its fabrication and storage in air-free environment,the sensor maintains its function with only minor performance loss.This fully printed,all-polymer biosensor with its ease of fabrication,accuracy,sensitivity and compatibility with easy-to-obtain biofluids such as saliva aids in the development of next generation low-cost,noninvasive,eco-friendly,and disposable diagnostic tools.展开更多
文摘Neuromorphic vision sensors have been extremely beneficial in developing energy-efficient intelligent systems for robotics and privacy-preserving security applications.There is a dire need for devices to mimic the retina's photoreceptors that encode the light illumination into a sequence of spikes to develop such sensors.Herein,we develop a hybrid perovskite-based flexible photoreceptor whose capacitance changes proportionally to the light intensity mimicking the retina's rod cells,paving the way for developing an efficient artificial retina network.The proposed device constitutes a hybrid nanocomposite of perovskites(methyl-ammonium lead bromide)and the ferroelectric terpolymer(polyvinylidene fluoride trifluoroethylene-chlorofluoroethylene).A metal-insulator-metal type capacitor with the prepared composite exhibits the unique and photosensitive capacitive behavior at various light intensities in the visible light spectrum.The proposed photoreceptor mimics the spectral sensitivity curve of human photopic vision.The hybrid nanocomposite is stable in ambient air for 129 weeks,with no observable degradation of the composite due to the encapsulation of hybrid perovskites in the hydrophobic polymer.The functionality of the proposed photoreceptor to recognize handwritten digits(MNIST)dataset using an unsupervised trained spiking neural network with 72.05%recognition accuracy is demonstrated.This demonstration proves the potential of the proposed sensor for neuromorphic vision applications.
文摘Inexpensive and easy-to-use diagnostic tools for fast health screening are imperative,especially in the developing world,where portability and affordability are a necessity.Accurate monitoring of metabolite levels can provide useful information regarding key metabolic activities of the body and detect the concomitant irregularities such as in the case of diabetes,a worldwide chronic disease.Today,the majority of daily glucose monitoring tools rely on piercing the skin to draw blood.The pain and discomfort associated with finger pricking have created a global need to develop non-invasive,portable glucose assays.In this work,we develop a disposable analytical device which can measure physiologically relevant glucose concentrations in human saliva based on enzymatic electrochemical detection.We use inkjet-printing technology for the rapid and low-cost deposition of all the components of this glucose sensor,from the electronics to the biorecognition elements,on commercially available paper substrates.The only electronic component of the sensor is the conducting polymer poly(3,4 ethylenedioxythiophene)doped with polystyrene sulfonate(PEDOT:PSS),while the biorecognition element comprises of the enzyme glucose oxidase coupled with an electron mediator.We demonstrate that one month after its fabrication and storage in air-free environment,the sensor maintains its function with only minor performance loss.This fully printed,all-polymer biosensor with its ease of fabrication,accuracy,sensitivity and compatibility with easy-to-obtain biofluids such as saliva aids in the development of next generation low-cost,noninvasive,eco-friendly,and disposable diagnostic tools.
