Showing papers by "Ying Fang published in 2019"

Elastocapillary self-assembled neurotassels for stable neural activity recordings

Abstract: Implantable neural probes that are mechanically compliant with brain tissue offer important opportunities for stable neural interfaces in both basic neuroscience and clinical applications. Here, we developed a Neurotassel consisting of an array of flexible and high–aspect ratio microelectrode filaments. A Neurotassel can spontaneously assemble into a thin and implantable fiber through elastocapillary interactions when withdrawn from a molten, tissue-dissolvable polymer. Chronically implanted Neurotassels elicited minimal neuronal cell loss in the brain and enabled stable activity recordings of the same population of neurons in mice learning to perform a task. Moreover, Neurotassels can be readily scaled up to 1024 microelectrode filaments, each with a neurite-scale cross-sectional footprint of 3 × 1.5 μm2, to form implantable fibers with a total diameter of ~100 μm. With their ultrasmall sizes, high flexibility, and scalability, Neurotassels offer a new approach for stable neural activity recording and neuroprosthetics.

Flexible and Implantable Microelectrodes for Chronically Stable Neural Interfaces.

Abstract: Implantable electrical probes that can record neural activities at single-neuron and sub-millisecond resolution are the most widely applied tools in both neuroscience research and neuroprosthetics. However, the structural and mechanical mismatch between conventional rigid probes and neural tissues results in inflammatory responses and signal degradation over chronic recordings. Reducing the cross-sectional footprints and rigidity of the probes can effectively improve the long-term stability of neural interfaces. Herein, recent progress in the development of implantable microelectrodes for chronically stable neural interfaces is highlighted, with a focus on the utilization of advanced materials and structural design concepts.

Binary Thiol-Capped Gold Nanoparticle Monolayer Films for Quantitative Surface-Enhanced Raman Scattering Analysis

Abstract: Surface-enhanced Raman scattering (SERS) can provide fingerprint information of analyte molecules with unparalleled sensitivity. However, quantitative analysis using SERS has remained one of the ma...

Acceptor-free photomultiplication-type organic photodetectors

Abstract: A series of organic photodetectors (OPDs) is prepared with two donor materials as active layers, with the only difference being the weight ratio of the two donors (one polymer and one small molecule). The OPDs work according to a photodiode model with an external quantum efficiency (EQE) of less than 10% at −10 V when the weight ratio of the two materials is 1 : 1 (wt/wt). The EQE of an OPD with P3HT:DRCN5T (100 : 2, wt/wt) as the active layer reaches 1400% at −10 V, exhibiting the photomultiplication (PM) phenomenon. The EQE values of PM-type OPDs can be markedly improved along with a bias increase, and the champion EQE reaches 10 600% at −20 V. The small number of small molecules can be used as electron traps due to the different lowest unoccupied molecular orbital (LUMO) levels of the two donors, and photogenerated electrons can be trapped in the small molecules surrounded by P3HT. The trapped electrons near the Al electrode can induce interfacial band bending for efficient hole tunneling injection from an external circuit. This work provides a new strategy for realizing acceptor-free PM-type OPDs, which may inspire us to further develop organic electronic devices with single type organic semiconducting materials.

Flexible Micropillar Electrode Arrays for In Vivo Neural Activity Recordings

Abstract: Flexible electronics that can form tight interfaces with neural tissues hold great promise for improving the diagnosis and treatment of neurological disorders and advancing brain/machine interfaces. Here, the facile fabrication of a novel flexible micropillar electrode array (µPEA) is described based on a biotemplate method. The flexible and compliant µPEA can readily integrate with the soft surface of a rat cerebral cortex. Moreover, the recording sites of the µPEA consist of protruding micropillars with nanoscale surface roughness that ensure tight interfacing and efficient electrical coupling with the nervous system. As a result, the flexible µPEA allows for in vivo multichannel recordings of epileptiform activity with a high signal-to-noise ratio of 252 ± 35. The ease of preparation, high flexibility, and biocompatibility make the µPEA an attractive tool for in vivo spatiotemporal mapping of neural activity.

Magnetic Actuation of Flexible Microelectrode Arrays for Neural Activity Recordings

Abstract: Implantable microelectrodes that can be remotely actuated via external fields are promising tools to interface with biological systems at a high degree of precision. Here, we report the development of flexible magnetic microelectrodes (FMμEs) that can be remotely actuated by magnetic fields. The FMμEs consist of flexible microelectrodes integrated with dielectrically encapsulated FeNi (iron-nickel) alloy microactuators. Both magnetic torque- and force-driven actuation of the FMμEs have been demonstrated. Nanoplatinum-coated FMμEs have been applied for in vivo recordings of neural activities from peripheral nerves and cerebral cortex of mice. Moreover, owing to their ultrasmall sizes and mechanical compliance with neural tissues, chronically implanted FMμEs elicited greatly reduced neuronal cell loss in mouse brain compared to conventional stiff probes. The FMμEs open up a variety of new opportunities for electrically interfacing with biological systems in a controlled and minimally invasive manner.

Photomultiplication type all-polymer photodetectors with single carrier transport property

Abstract: Photomultiplication (PM) type all-polymer photodetectors (all-PPDs) are first demonstrated with the sandwich structure of ITO/PEDOT:PSS/PBDB-T:PZ1 (100: x , wt/wt)/Al. The optimal PM type all-PPDs with PBDB-T:PZ1 (100:3, wt/wt) as active layers exhibit external quantum efficiency (EQE) of >100% in the spectral range from 310 to 790 nm. Under 675 nm light illumination, the champion EQE value arrives to 1,470% at −20 V bias and the specific detectivity approaches 1× 1012 Jones at −10 V bias. The PM phenomenon in all-PPDs results from hole tunneling injection assisted by interfacial band bending induced by trapped electrons in PZ1 near Al electrode. The EQE values of optimal PM type all-PPDs still remained over 90% of the original value after 60 d of the storage in a high-purity nitrogen-filled glove box.

Treatment method of implanted flexible neural microelectrode comb

Abstract: The invention provides a treatment method of an implanted flexible neural microelectrode comb. The treatment method comprises the steps that a solid structure, a grid structure and a comb-shaped structure in the implanted flexible neural microelectrode comb are immersed in a curing agent, the implanted flexible neural microelectrode comb is taken out of the curing agent to make the grid structureand the comb-shaped structure bend, the grid structure is subjected to self-assembly, and the comb-shaped structure is self-assembled to form a needle-like structure. By means of the treatment method,the two-dimensional planar flexible neural microelectrode comb can be assembled to form a flexible neural microelectrode comb with a three-dimensional structure, damage caused in an implanting process can be greatly reduced, compared with a dispensing method where the flexible neural microelectrode comb is treated, the immersing method has the advantages that the flexible neural microelectrode comb treated by using the immersing method has a more orderly structure after being assembled, the formed needle-like structure has a smaller diameter and a more smooth surface, the damage caused in theelectrode implanting process is smaller, and the implanted flexible neural microelectrode comb is more suitable for being used as a cranial nerve detecting element.