Cell Segmentation and Tracking in Microfluidic Platform

In this research, we have concentrated on trajectory extraction based on image segmentation and data association in order to provide an economic and complete solution for rapid microfluidic cell migration experiments. We applied region scalable active contour model to segment the individual cells and then employed the ellipse fitting technique to process touching cells. Subsequently, we have also introduced a topology based technique to associate the cells between consecutive frames. This scheme achieves satisfactory segmentation and tracking results on the datasets acquired by our microfluidic platform.

3D free-assembly modular microfluidics inspired by movable type printing

Reconfigurable modular microfluidics presents an opportunity for flexibly constructing prototypes of advanced microfluidic systems.Nevertheless,the strategy of directly integrating modules cannot easily fulfill the requirements of common applications,e.g.,the incorporation of materials with biochemical compatibility and optical transparency and the execution of small batch production of disposable chips for laboratory trials and initial tests.Here,we propose a manufacturing scheme inspired by the movable type printing technique to realize 3D free-assembly modular microfluidics.Double-layer 3D microfluidic structures can be produced by replicating the assembled molds.A library of modularized molds is presented for flow control,droplet generation and manipulation and cell trapping and coculture.In addition,a variety of modularized attachments,including valves,light sources and microscopic cameras,have been developed with the capability to be mounted onto chips on demand.Microfluidic systems,including those for concentration gradient generation,droplet-based microfluidics,cell trapping and drug screening,are demonstrated.This scheme enables rapid prototyping of microfluidic systems and construction of on-chip research platforms,with the intent of achieving high efficiency of proof-of-concept tests and small batch manufacturing.

16.3%Efficiency binary all-polymer solar cells enabled by a novel polymer acceptor with an asymmetrical selenophene-fused backbone

Despite the significant progress made recently in all-polymer solar cells(all-PSCs),it is still quite challenging to achieve high open-circuit voltage(V_(oc))and short-circuit current density(J_(sc))simultaneously in order to further improve their performance.The recent strategy of using selenophene to replace thiophene on the Y6 based polymer acceptors has resulted in significantly improved J_(sc)s of the resulting all-PSCs.However,such modifications have also depressed V_(oc),which compromises the overall performance of the devices.Herein,we present the design and synthesis of a novel polymer acceptor,PYT-1S1Se,created by inserting an asymmetrical selenophene-fused framework to precisely manipulate optical absorption and electronic properties.Compared with the selenium-free analog,PYT-2S,and symmetrical selenium-fused analog,PYT-2Se,the PYT-1S1Se derived all-PSCs not only deliver optimized J_(sc)(24.1 mA cm^(−2))and V_(oc)(0.926 V)metrics,but also exhibit a relatively low energy loss of 0.502 eV.Consequently,these devices obtain a record-high power conversion efficiency(PCE)of 16.3%in binary all-PSCs.This work demonstrates an effective molecular design strategy for balancing the trade-off between V_(oc) and J_(sc) to achieve highefficiency all-PSCs.

Label-free 3D computational imaging of spermatozoon locomotion, head spin and flagellum beating over a large volume

We report a high-throughput and label-free computational imaging technique that simultaneously measures in three-dimensional(3D)space the locomotion and angular spin of the freely moving heads of microswimmers and the beating patterns of their flagella over a sample volume more than two orders-of-magnitude larger compared to existing optical modalities.Using this platform,we quantified the 3D locomotion of 2133 bovine sperms and determined the spin axis and the angular velocity of the sperm head,providing the perspective of an observer seated at the moving and spinning sperm head.In this constantly transforming perspective,flagellum-beating patterns are decoupled from both the 3D translation and spin of the head,which provides the opportunity to truly investigate the 3D spatio-temporal kinematics of the flagellum.In addition to providing unprecedented information on the 3D locomotion of microswimmers,this computational imaging technique could also be instrumental for micro-robotics and sensing research,enabling the high-throughput quantification of the impact of various stimuli and chemicals on the 3D swimming patterns of sperms,motile bacteria and other micro-organisms,generating new insights into taxis behaviors and the underlying biophysics.

Broadband photomultiplication-type polymer photodetectors and its application in light-controlled circuit

Photomultiplication-type polymer photodetectors(PM-PPDs)were achieved with polymer P3HT as donor and PY3Se-1V as acceptor based on structure of ITO/PEDOT:PSS/active layer/Al.The optimal weight ratio of P3HT to PY3Se-1V is about 100:3.Amounts of isolated electron traps are formed with PY3Se-1V surrounded by P3HT due to rather less content of PY3Se-1V in active layers and about 0.94 e V energy offset between the lowest unoccupied molecular orbitals(LUMO)of P3HT and PY3Se-1V.The optimal PM-PPDs exhibit broad spectral response from 350 to 950 nm and external quantum efficiency(EQE)values of68,200%at 360 nm,26,400%at 630 nm and 19,500%at 850 nm under-15 V bias.The working mechanism of PM-PPDs is attributed to the interfacial trap-assisted hole tunneling injection from external circuit.The performance of PM-PPDs can be further improved by incorporating appropriate PMBBDT with high hole mobility as the third component.The EQE values of optimal ternary PM-PPDs are increased to 105,000%at 360 nm,40,000%at 630 nm and 31,800%at 850 nm under-15 V bias,benefiting from the enhanced hole transport in ternary active layers.The optimal ternary PM-PPDs were successfully applied in a light-controlled circuit to turn on or turn off light emitting diode(LED).

Recent advances in acoustofluidic separation technology in biology

Acoustofluidic separation of cells and particles is an emerging technology that integrates acoustics and microfluidics.In the last decade,this technology has attracted significant attention due to its biocompatible,contactless,and labelfree nature.It has been widely validated in the separation of cells and submicron bioparticles and shows great potential in different biological and biomedical applications.This review first introduces the theories and mechanisms of acoustofluidic separation.Then,various applications of this technology in the separation of biological particles such as cells,viruses,biomolecules,and exosomes are summarized.Finally,we discuss the challenges and future prospects of this field.

The Potential Game-Changer:A Concept-to-Proof Study on D:A Heterojunction-Free Organic Photovoltaics

Since 1986,the donor-acceptor (D:A) heterojunction has been regarded a necessity for high-efficiency organic photovoltaics (OPVs),due to its unique advantage in compensating the intrinsic limitations of organic semiconductors,such as high exciton binding energy and poor ambipolar charge mobility. While this adversely causes tremendous non-radiative charge recombination and instability issues,which currently become the most critical limits for commercialization of OPVs. Here,we present a concept-to-proof study on the potential of D:A heterojunction free OPV by taking advantage of recent progress of non-fullerene acceptors. First,we demonstrate that the “free carriers” can be spontaneously generated upon illumination in an NFA,i.e.,the 6TIC-4F single layer. Second,the 6TIC-4F layer also exhibits good ambipolar charge transporting property. These exceptional characteristics distinguish it from the traditional organic semiconductors,and relieve it from the reliance of D:A heterojunction to independently work as active layer. As a result,the subsequent OPV by simply sandwiching the 6TIC-4F layer between the cathode and anode yields a considerably high power conversion efficiency ~1%. Moreover,we find the D:A heterojunction free device exhibits two order of magnitude higher electroluminescence quantum efficiency and significantly reduced VOC loss by 0.16 eV compared to those of the D:A BHJ structure,validating its promise for higher efficiency in the future. Therefore,our work demonstrates the possibility of using D:A heterojunction-free device structure for high performance,that can potentially become the next game changer of OPV.