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
To address the current limitations of time-gated Raman spectroscopy,specifically its narrow spectral range and low spectral resolution,and simultaneously acquire Raman and fluorescence life-time images,we have develop...To address the current limitations of time-gated Raman spectroscopy,specifically its narrow spectral range and low spectral resolution,and simultaneously acquire Raman and fluorescence life-time images,we have developed a Fourier-transform photon counting spectroscopy platform.A Mach-Zehnder interferometer employing a high accuracy linear motor stage was combined with photon-counting avalanche diodes and time-tagged acquisition,allowing to sort photons into a matrix of stage positions determined using their coarse arrival time with 50 ns steps of the excitation laser repetition period,and a fine arrival time of 80 ps resolution relative to the excitation pulse of 100 ps duration.The instrument achieves a time resolution of 547 ps,a wide spectral range of−1000 to 10,000 cm−1 Raman shift from the excitation at 532 nm wavelength,and a high spectral resolution of 0.05 cm−1.For experimental validation,we used fluorescently coated silicon wafers and fluorescent plastic microspheres.Raman signal was observed during the laser excitation pulse within the time-resolution,while fluorescence signals dominate afterwards.The results confirm that the instrument can effectively separate Raman and fluorescence signals.展开更多
Natural creatures that enables controllable liquid transport provides the inspiration fordeveloping novel microfluidic devices by engineering functional surfaces withsuperwettability. However, towards microfluidic app...Natural creatures that enables controllable liquid transport provides the inspiration fordeveloping novel microfluidic devices by engineering functional surfaces withsuperwettability. However, towards microfluidic applications, the strict requirements ofsophisticated droplet manipulation make it challenging to reach this end. In this work,we report a conceptually new self-propelled droplet manipulation strategy based onreconfigurable superhydrophobic chips. The modular droplet chip (MDC) is developedby laser embossing a series of superhydrophobic structures on elastomer jigsaws thatact as functional units. MDC is potable since only gravity is used as the driving force fordynamic manipulation of liquid droplets, including droplets transporting, splitting,merging and bouncing without mass loss. The MDC demonstrated reasonable anticross-contamination property due to the water repellence of the superhydrophobicity.Modular assembly of MDC enables different chip functions including solution dilution,SERS detection, cell labeling and chemical synthesis. As a miniature and portableexperimental platform, the MDC is promising for next-generation lab-on-a-chip systems.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Funded by Chinese Academy of Sciences President’s International Fellowship Initiative.Grant No.2022VBA0028.
文摘To address the current limitations of time-gated Raman spectroscopy,specifically its narrow spectral range and low spectral resolution,and simultaneously acquire Raman and fluorescence life-time images,we have developed a Fourier-transform photon counting spectroscopy platform.A Mach-Zehnder interferometer employing a high accuracy linear motor stage was combined with photon-counting avalanche diodes and time-tagged acquisition,allowing to sort photons into a matrix of stage positions determined using their coarse arrival time with 50 ns steps of the excitation laser repetition period,and a fine arrival time of 80 ps resolution relative to the excitation pulse of 100 ps duration.The instrument achieves a time resolution of 547 ps,a wide spectral range of−1000 to 10,000 cm−1 Raman shift from the excitation at 532 nm wavelength,and a high spectral resolution of 0.05 cm−1.For experimental validation,we used fluorescently coated silicon wafers and fluorescent plastic microspheres.Raman signal was observed during the laser excitation pulse within the time-resolution,while fluorescence signals dominate afterwards.The results confirm that the instrument can effectively separate Raman and fluorescence signals.
基金National Key Research and Development Program of China(2017YFB1104300)National Natural Science Foundation of China(61935008,61522503,61590930,61775078,and 61605055).
文摘Natural creatures that enables controllable liquid transport provides the inspiration fordeveloping novel microfluidic devices by engineering functional surfaces withsuperwettability. However, towards microfluidic applications, the strict requirements ofsophisticated droplet manipulation make it challenging to reach this end. In this work,we report a conceptually new self-propelled droplet manipulation strategy based onreconfigurable superhydrophobic chips. The modular droplet chip (MDC) is developedby laser embossing a series of superhydrophobic structures on elastomer jigsaws thatact as functional units. MDC is potable since only gravity is used as the driving force fordynamic manipulation of liquid droplets, including droplets transporting, splitting,merging and bouncing without mass loss. The MDC demonstrated reasonable anticross-contamination property due to the water repellence of the superhydrophobicity.Modular assembly of MDC enables different chip functions including solution dilution,SERS detection, cell labeling and chemical synthesis. As a miniature and portableexperimental platform, the MDC is promising for next-generation lab-on-a-chip systems.
