Droplet microfluidics have found increasing applications across many fields.While droplet generation at a T-junction is a common method,its reliance on trial-and-error operation imposes undesirable constraints on its ...Droplet microfluidics have found increasing applications across many fields.While droplet generation at a T-junction is a common method,its reliance on trial-and-error operation imposes undesirable constraints on its performance and applicability.In this study,we demonstrate a simple method for on-demand droplet formation at a T-junction with precise temporal control over individual droplet formation.Based on experimental observations,we also develop a physical model to describe the relationships among pressures,droplet generation,device geometry,and interfacial properties.Experimental validation demonstrates excellent performance of the model in predicting the pressure thresholds for switching droplet generation on and off.To address parameter uncertainties arising from real-world complexities,we show that monitoring droplet generation frequency provides a rapid,in situ approach for optimising experimental conditions.Our findings offer valuable guidelines for the design and automation of robust droplet-on-demand microfluidic systems,which can be readily implemented in conventional laboratories for a broad range of applications.展开更多
Confocal Raman microscopy is currently used for label-free optical sensing and imaging within the biological,engineering,and physical sciences as well as in industry.However,currently these methods have limitations,in...Confocal Raman microscopy is currently used for label-free optical sensing and imaging within the biological,engineering,and physical sciences as well as in industry.However,currently these methods have limitations,including their low spatial resolution and poor focus stability,that restrict the breadth of new applications.This paper now introduces differential-confocal controlled Raman microscopy as a technique that fuses differential confocal microscopy and Raman spectroscopy,enabling the point-to-point collection of three-dimensional nanoscale topographic information with the simultaneous reconstruction of corresponding chemical information.The microscope collects the scattered Raman light together with the Rayleigh light,both as Rayleigh scattered and reflected light(these are normally filtered out in conventional confocal Raman systems).Inherent in the design of the instrument is a significant improvement in the axial focusing resolution of topographical features in the image(to^1 nm),which,when coupled with super-resolution image restoration,gives a lateral resolution of 220 nm.By using differential confocal imaging for controlling the Raman imaging,the system presents a significant enhancement of the focusing and measurement accuracy,precision,and stability(with an antidrift capability),mitigating against both thermal and vibrational artefacts.We also demonstrate an improved scan speed,arising as a consequence of the nonaxial scanning mode.展开更多
The specific and multiplexed detection of DNA underpins many analytical methods,including the detection of microorganisms that are important in the medical,veterinary,and environmental sciences.To achieve such measure...The specific and multiplexed detection of DNA underpins many analytical methods,including the detection of microorganisms that are important in the medical,veterinary,and environmental sciences.To achieve such measurements generally requires enzyme-mediated amplification of the low concentrations of the target nucleic acid sequences present,together with the precise control of temperature,as well as the use of enzyme-compatible reagents.This inevitably leads to compromises between analytical performance and the complexity of the assay.The hybridization chain reaction(HCR)provides an attractive alternative,as a route to enzyme-free DNA amplification.To date,the linear nucleic acid products,produced during amplification,have not enabled the development of efficient multiplexing strategies,nor the use of label-free analysis.Here,we show that by designing new DNA nanoconstructs,we are able,for the first time,to increase the molecular dimensionality of HCR products,creating highly branched amplification products,which can be readily detected on label-free sensors.To show that this new,branching HCR system offers a route for enzyme-free,label-free DNA detection,we demonstrate the multiplexed detection of a target sequence(as the initiator)in whole blood.In the future,this technology will enable rapid point-of-care multiplexed clinical analysis or in-the-field environmental monitoring.展开更多
文摘Droplet microfluidics have found increasing applications across many fields.While droplet generation at a T-junction is a common method,its reliance on trial-and-error operation imposes undesirable constraints on its performance and applicability.In this study,we demonstrate a simple method for on-demand droplet formation at a T-junction with precise temporal control over individual droplet formation.Based on experimental observations,we also develop a physical model to describe the relationships among pressures,droplet generation,device geometry,and interfacial properties.Experimental validation demonstrates excellent performance of the model in predicting the pressure thresholds for switching droplet generation on and off.To address parameter uncertainties arising from real-world complexities,we show that monitoring droplet generation frequency provides a rapid,in situ approach for optimising experimental conditions.Our findings offer valuable guidelines for the design and automation of robust droplet-on-demand microfluidic systems,which can be readily implemented in conventional laboratories for a broad range of applications.
基金Key Program of National Natural Science Foundation of China(51535002,61635003)Engineering and Physical Sciences Research Council(EP/P001114/1)。
文摘Confocal Raman microscopy is currently used for label-free optical sensing and imaging within the biological,engineering,and physical sciences as well as in industry.However,currently these methods have limitations,including their low spatial resolution and poor focus stability,that restrict the breadth of new applications.This paper now introduces differential-confocal controlled Raman microscopy as a technique that fuses differential confocal microscopy and Raman spectroscopy,enabling the point-to-point collection of three-dimensional nanoscale topographic information with the simultaneous reconstruction of corresponding chemical information.The microscope collects the scattered Raman light together with the Rayleigh light,both as Rayleigh scattered and reflected light(these are normally filtered out in conventional confocal Raman systems).Inherent in the design of the instrument is a significant improvement in the axial focusing resolution of topographical features in the image(to^1 nm),which,when coupled with super-resolution image restoration,gives a lateral resolution of 220 nm.By using differential confocal imaging for controlling the Raman imaging,the system presents a significant enhancement of the focusing and measurement accuracy,precision,and stability(with an antidrift capability),mitigating against both thermal and vibrational artefacts.We also demonstrate an improved scan speed,arising as a consequence of the nonaxial scanning mode.
基金the James Watt Nanofabrication Centre for help with device fabrication and Dr Xiaofei Yuan for help with surface chemistry.The work was supported by EPSRC(EP/I017887/1 and EP/K027611/1)ERC 340117JR acknowledges a University of Glasgow Fellowship and GX a College Scholarship(UG).
文摘The specific and multiplexed detection of DNA underpins many analytical methods,including the detection of microorganisms that are important in the medical,veterinary,and environmental sciences.To achieve such measurements generally requires enzyme-mediated amplification of the low concentrations of the target nucleic acid sequences present,together with the precise control of temperature,as well as the use of enzyme-compatible reagents.This inevitably leads to compromises between analytical performance and the complexity of the assay.The hybridization chain reaction(HCR)provides an attractive alternative,as a route to enzyme-free DNA amplification.To date,the linear nucleic acid products,produced during amplification,have not enabled the development of efficient multiplexing strategies,nor the use of label-free analysis.Here,we show that by designing new DNA nanoconstructs,we are able,for the first time,to increase the molecular dimensionality of HCR products,creating highly branched amplification products,which can be readily detected on label-free sensors.To show that this new,branching HCR system offers a route for enzyme-free,label-free DNA detection,we demonstrate the multiplexed detection of a target sequence(as the initiator)in whole blood.In the future,this technology will enable rapid point-of-care multiplexed clinical analysis or in-the-field environmental monitoring.
