A Hemispherical Image Sensor Array Fabricated with Organic Photomemory Transistors

Hemispherical image sensors simplify lens designs, reduce optical aberrations, and improve image resolution for compact wide-field-of-view cameras. To achieve hemispherical image sensors, organic materials are promising candidates due to the following advantages: tunability of optoelectronic/spectral response and low-temperature low-cost processes. Here, a photolithographic process is developed to prepare a hemispherical image sensor array using organic thin film photomemory transistors with a density of 308 pixels per square centimeter. This design includes only one photomemory transistor as a single active pixel, in contrast to the conventional pixel architecture, consisting of select/readout/reset transistors and a photodiode. The organic photomemory transistor, comprising light-sensitive organic semiconductor and charge-trapping dielectric, is able to achieve a linear photoresponse (light intensity range, from 1 to 50 W m⁻²), along with a responsivity as high as 1.6 A W⁻¹ (wavelength = 465 nm) for a dark current of 0.24 A m⁻² (drain voltage = −1.5 V). These observed values represent the best responsivity for similar dark currents among all the reported hemispherical image sensor arrays to date. A transfer method was further developed that does not damage organic materials for hemispherical organic photomemory transistor arrays. These developed techniques are scalable and are amenable for other high-resolution 3D organic semiconductor devices.     

帕尔贴石墨烯3D打印快速冷冻成型平台设计

本文基于帕尔贴制冷片研制出一种新型石墨烯材料3D打印快速冷冻成型平台,它具有低噪音、重量轻、高可靠性及结构紧凑等优点。利用该平台进行了初步实验并确定了控制策略,采用模糊-PID控制方法对快速冷冻成型平台温度进行控制实验研究。6组实验结果表明:该快速冷冻成型平台能使平台温度在-40～0℃之间连续可调,超调量在4.8%以内。-5、-10、-15、-20、-30、-40℃的超调量分别为4.8%、3.9%、3.3%、2.8%、2.2%、0,调节时间为88、94、106、124、76、92 s。在设定值附近几乎保持恒定,成型平台表面无温度梯度存在。石墨烯浆料成型精度高,满足石墨烯3D打印成型要求。     

Nondestructive Real‐Time Monitoring of Enhanced Stem Cell Differentiation Using a Graphene‐Au Hybrid Nanoelectrode Array

Stem cells have attracted increasing research interest in the field of regenerative medicine because of their unique ability to differentiate into multiple cell lineages. However, controlling stem cell differentiation efficiently and improving the current destructive characterization methods for monitoring stem cell differentiation are the critical issues. To this end, multifunctional graphene–gold (Au) hybrid nanoelectrode arrays (NEAs) to: (i) investigate the effects of combinatorial physicochemical cues on stem cell differentiation, (ii) enhance stem cell differentiation efficiency through biophysical cues, and (iii) characterize stem cell differentiation in a nondestructive real‐time manner are developed. Through the synergistic effects of physiochemical properties of graphene and biophysical cues from nanoarrays, the graphene‐Au hybrid NEAs facilitate highly enhanced cell adhesion and spreading behaviors. In addition, by varying the dimensions of the graphene‐Au hybrid NEAs, improved stem cell differentiation efficiency, resulting from the increased focal adhesion signal, is shown. Furthermore, graphene‐Au hybrid NEAs are utilized to monitor osteogenic differentiation of stem cells electrochemically in a nondestructive real‐time manner. Collectively, it is believed the unique multifunctional graphene‐Au hybrid NEAs can significantly advance stem‐cell‐based biomedical applications.     

Roll-Pressed Silicon Anodes with High Reversible Volumetric Capacity Achieved by Interfacial Stabilization and Mechanical Strengthening of a Silicon/Graphene Hybrid Assembly

Application of Si anodes is hindered by severe capacity fading due to pulverization of Si particles during the large volume changes of Si during charge/discharge and repeated formation of the solid-electrolyte interphase. To address these issues, considerable efforts have been devoted to the development of Si composites with conductive carbons (Si/C composites). However, Si/C composites with high C content inevitably show low volumetric capacity because of low electrode density. For practical applications, the volumetric capacity of a Si/C composite electrode is more important than gravimetric capacity, but volumetric capacity in pressed electrodes is rarely reported. Herein, a novel synthesis strategy is demonstrate for a compact Si nanoparticle/graphene microspherical assembly with interfacial stability and mechanical strength achieved by consecutively formed chemical bonds using 3-aminopropyltriethoxysilane and sucrose. The unpressed electrode (density: 0.71 g cm⁻³) shows a reversible specific capacity of 1470 mAh g⁻¹ with a high initial coulombic efficiency of 83.7% at a current density of 1 C-rate. The corresponding pressed electrode (density: 1.32 g cm⁻³) exhibits high reversible volumetric capacity of 1405 mAh cm⁻³ and gravimetric capacity of 1520 mAh g⁻¹ with a high initial coulombic efficiency of 80.4% and excellent cycling stability of 83% over 100 cycles at 1 C-rate.     

微光成象系统中实时降噪的优化设计

微光电视工作于极低照度或恶劣环境下，输出信噪比明显降低，目标完全淹没在背景噪声中，使探测率大大下降。提出了用帧间处理技术消除加性噪声。论述了字长和滤波系数的选择原则。研究了实时去噪的几项关键技术，算法和符号位的设计，各部分工作时间分配以及大背景噪声下时种同步方法。     

采用可编程器件设计伺服系统的指令脉冲

交流伺服驱动动系统包括三种指令形式,即脉冲指令,速度指令,转矩指令。结合实际的 应用,采用模拟量脉冲指令的形式对整个伺服驱动系统加以控制。为此,使用XILINX公司生产的XCS20TQ144芯片设计硬件电路,并结合伺服软件算法,得到了满足实际需求的直线型加速曲线,指数型加速曲线和铃状型加速曲线。