In order to achieve a low-cost, simple, fast, and green preparation method of graphene quantum dots (GQDs), a method for one-step preparation of GQDs by laser-induced polyimide powder was proposed. By controlling the laser parameters and using low-cost precursor material polyimide (PI) powder, a bright blue fluorescent GQDs solution was successfully prepared, and the whole experimental process was simulated by ReaxFF molecular reaction dynamics. The results show that the GQDs solution with blue fluorescent can be prepared by laser -induced PI power in one step. The scraped black matter contained GQDs. After the samples were tested by UV-vis, PL, TEM, and Raman, the prepared GQDs had an average particle size of 6.14 nm, a quantum yield of about 11.4%, and stable fluorescence properties. The whole process of the proposed method can be carried out at ambient temperature without any other chemical reagents or complicated subsequent processing, and has the advantages of simplicity, rapidity, environmental protection, and low cost, which not only provides a new reference for the green synthesis of quantum, but also has the potential for large-scale production.

提出了一种既具有抗伽马(γ)辐照又具有电磁屏蔽性能的氧化钨(WO3)/石墨烯泡沫(GF)/聚二甲基硅氧烷(PDMS)复合力敏结构.该结构以GF良好的三维多孔网状结构所形成的良好导电网络来实现电磁屏蔽.WO3粉填充来实现γ辐照屏蔽.通过真空辅助法,将WO3/PDMS溶液回填进入GF中制得.通过60Co-γ射线对复合结构进行不同剂量的辐照,并对辐照前后复合结构的电磁屏蔽性能、电导率及力敏特性进行了测试分析.结果表明:所制备的复合结构随着辐照剂量的增加,依旧保持较好的电磁屏蔽效能、导电性和良好的重复性与稳定性.该复合力敏结构具有较好的γ屏蔽效果和电磁屏蔽性能,为柔性可穿戴器件应用于辐照及电磁辐射环境中提供了参考.

The optical properties of CdSe/ZnS quantum dots(QDs)embedded in polydimethylsiloxane(PDMS)flexible materials after irradiated with γ-rays were studied.As an embedding matrix,PDMS exhibits the advantage of high radiation hardness.The luminescence spectra and fluorescence lifetime of the irradiated and unirradiated samples were tested.The fluorescence intensity of QDs decreases with the increase of the irradiation dose according to the result of luminescence spectra.The fluorescence intensity of the QDs decreases by 80％after irradiation with a dose of 1 kGy,but the position of the emission peak and the spectral shape of the QDs remain consistent before and after irradiation.In addition,the fluorescence lifetime of QDs is shortened after irradiation.Based on the fluorescence response of QDs to the irradiation of y-rays and combined with flexible materials,our work provides a theoretical basis for the application of QDs as a new wearable dosimeter.

In this study, a graphene foam/polydimethylsiloxane (GF/PDMS) force-sensitive composite with excellent electrical, mechanical, and electromagnetic interference (EMI) shielding performances was prepared. GF with different contents of graphene was prepared by chemical vapor deposition (CVD) and GF/PDMS composites were prepared by vacuum-assisted impregnation. The electrical test and morphology detection indicated good conductivity and flexibility of the proposed composite. Indeed, the GF/PDMS composite with 0.4 wt% graphene had the highest conductivity (4 S cm−1). The EMI shielding performance of the GF/PDMS composite with 0.4 wt% graphene in the X-band was tested and its EMI shielding effectiveness (SE) was 32 dB. After repeated bending for 10000 times, the EMI SE of the proposed composite exhibited negligible changes. The force sensitivity test showed that the sensitivity of the proposed composite was 8.7 KPa−1 under the tensile strain of 30%–50%. Under the pressure of 600–1000 KPa, the sensitivity of the proposed composite was 0.15 KPa−1. Under the stress of 1000 KPa, the EMI shielding coefficient of the proposed composite was 25 dB, which was reduced by 21.9%. The results demonstrated that GF/PDMS with low filler contents (0.4 wt%) exhibited high conductivity (4 S cm−1), high EMI SE (32 dB), and excellent mechanical properties.

In order to obtain a force-sensitive composite structure with high-performance electromagnetic interference (EMI) shielding, this paper proposes a method for preparing flexible force-sensitive composites by backfilling PDMS into a carbon nanotube (CNT) sponge using a vacuum-assisted method. Compared with CNTs/PDMS force-sensitive composites with different content prepared by the traditional solution blending method, the CNT sponge/PDMS force-sensitive composite prepared by the vacuum-impregnation method demonstrated sensitivity of 70 in a strain range of 35–50

In this paper, a carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite force-sensitive structure with good flexibility is proposed and fabricated, and the measurement of scanning electron microscopy (SEM) and Raman are carried out. The equivalent circuit of force-sensitive test of structure is performed and analyzed under direct current (DC) and alternating current (AC) conditions. Under AC conditions, experimental results further show that the sensitivity and sensitivity factors of force-sensitive structures are 0.15 KPa−1 and 2.17 in the pressure range of 600–1000 KPa compressive stress and 20–50% tensile stress, respectively. These results are increased by 36.4% and 38.2% compared to the results of compressive stress (0.11 KPa−1) and tensile stress (1.57) under DC conditions, respectively. It shows that the carbon nanotube/PDMS composite has higher test accuracy under AC conditions.

This study aimed to design a polydimethylsiloxane multi-walled carbon nanotube composite force-sensitive structure. Five composite materials with different volume fractions of carbon nanotubes were prepared, and the microscopic morphology of the samples recorded. Conductive pathways were formed inside the composite materials. The force-sensitive performance was verified through tensile experiments on the material. The sample with a content of 3 vol. % had a sensitivity of up to 165, which was good for detecting small strains. The samples were irradiated with 60Co-γ rays, and the irradiation doses were 5, 10, 20, 50, and 100 kGy. After irradiation with the highest dose of 100 kGy, the sensitivity of the sample with a content of 3 vol. % was reduced to 125. The samples exposed to different irradiation doses were stretched and released 3000 times to verify the repeatability of the force sensitive characteristics; almost no difference was found in the resistance strain results of the sample. Experiments showed that the designed composite force-sensitive structure had high sensitivity, good repeatability, and good resistance to gamma radiation.

This paper proposes a new type of flexible force-sensitive structure that is resistant to gamma radiation and is made of tungsten oxide (WO3) powder, polydimethylsiloxane (PDMS), and carbon nanotube (CNT) sponge. The thickness of the sample was 2.2 mm, the middle interlayer was composed of a carbon nanotube (CNT) sponge and PDMS to form a conductive layer, and the upper and lower layers were made of tungsten oxide and PDMS, which formed a gamma-ray shielding layer. When the particle size of the tungsten oxide powder was 50 nm, 100 nm, and 1 µm, the composite force-sensitive structure exhibited better force-sensitive performance. The composite force-sensitive structure was irradiated with doses of 5, 20, 50, and 100 KGy through 60Co- rays with an energy of 1.25 MeV. The results showed that the force-sensitive characteristics changed little in significance after irradiation by different doses of gamma rays, indicating that the force-sensitive structure has good resistance to gamma radiation. This flexible stress sensor can be used in soft robots and health inspection, even in harsh environments without significant performance loss.

This paper studied the radiation hardness of InAs Quantum Dot(QD) embedded in high electron mobility transistor (HEMT) for force-sensitive structure, and further verified its high irradiation properties and high sensitivity. The transfer characteristics, output characteristics, structural changes and force-sensitivity of InAs QD-HEMT and HEMT structure are analyzed after irradiated with 1900-Mev 181Ta ions at different fluences. The experiment results of electrical characterization indicated that the radiation hardness of InAs QD-HEMT was 3.5 times higher than that of HEMT. The mechanical sensitivity of pristine InAs QD-HEMT structure was 0.153 mA/KPa, which was higher than that of pristine HEMT structure by 0.088mA/KPa, and the force-sensitivity of InAs QD-HEMT structure was less affected by irradiation. The results indicate that InAs QD-HEMT force-sensitive structure has a strong tolerance to heavy ion irradiation. The irradiation hardens, and force-sensitive characteristics of the device can be improved by using InAs QD-HEMT structure, which can provide radiation protection for MEMS sensors applied in a harsh radiation environment.

采用简单、绿色、低成本的方法合成石墨烯量子点(GQDs)一直是研究者们不断追求和探究的热点.本文首先采用简单、低成本的激光诱导聚二甲基硅氧烷(PDMS)方法成功制备出有缺陷的少层石墨烯,然后再以所制备的石墨烯为碳源,采用一步水热法成功制备出了分散性良好、横向平均尺寸约为6.67 nm、发稳定蓝色荧光的GQDs溶液.分别采用透射电镜(TEM)、拉曼光谱、紫外吸收光谱和荧光光谱对GQDs的形貌和荧光特性进行了表征.以硫酸奎宁为标准参考物,计算所得GQDs的荧光量子产率约为6.3％.本研究提出的制备GQDs的方法具有简单、低成本、低污染的优势,为石墨烯量子点的制备提供了一种新途径、新参考,也为石墨烯量子点大规模商业化制备提供了潜力.

辐射对空间通信系统中使用的传感器件的不利影响是需要重点考虑的问题,作为力学传感器件的核心部件,对力敏传感单元的抗辐照特性的研究就尤为重要.设计了一种InAs量子点(QD)嵌入式高电子迁移率晶体管(HEMT)力敏结构,通过60Co-γ射线对InAs QD-HEMT结构进行了不同剂量的辐照,并对辐照前后结构的电学特性、力敏特性进行了测试分析.实验结果表明:随着辐照剂量的增加,InAs QD-HEMT结构的电学特性发生退化,灵敏度不断降低.经过150 Mrad剂量辐照后InAs QD-HEMT结构的漏极电流降低了约21％,灵敏度降低了63.4％.结果表明:高剂量辐照后InAs QD-HEMT结构仍具有工作性能,为MEMS传感器应用于强辐照环境提供研究基础.

A force-sensitive structure of an InAs Quantum Dot (QD) embedded in a high electron mobility transistor (HEMT) is presented in this paper. The size of an InAs QD is about 30 nm prepared by the S-K growth mode, and the force-sensitive structure is fabricated by molecular beam epitaxy (MBE). The force-sensitivity characteristic of the QD HEMT is studied by the electrical and mechanical properties. The electrical characteristics show that the InAs QD-HEMT has linear, cut-off, and saturation operating states, and produces different output currents under different gate voltages, which shows that the structure is reasonable. Furthermore, the results of the output characteristics under different pressure show that the output voltage of the QD-HEMT decreases with the increase in pressure, which indicates that the InAs QD-HEMT has a vital mechanical–electrical coupling characteristic. The output voltage of the InAs QD-HEMT in the range of 0–100 kPa shows that the sensitivity was 1.09 mV/kPa.

A method of detecting the single channel triaxial magnetic field information based on diamond nitrogen-vacancy (NV) color center is introduced. Firstly, the incident angle of the bias magnetic field which can achieve the equal frequency difference optically-detected magnetic resonance (ODMR) spectrum of diamond NV color center is calculated theoretically, and the triaxial magnetic information solution model is also constructed. Secondly, the microwave time-controlled circuit module is designed to generate equal timing and equal frequency difference microwave pulse signals in one channel. Combining with the optical detection magnetic resonance technology, the purpose of sequentially locking and detecting the four formant signals on one side of the diamond NV color center (m s = –1 state signal) is achieved, and the vector magnetic field information detection is accomplished by combining the triaxial magnetic information solution model. The system can obtain magnetic field detection in a range of 0 mT–0.82 mT. The system’s magnetic noise sensitivity is 14.2 nT/Hz1/2, and the deviation angle errors of magnetic field detection θx and θy are 1.3° and 8.2° respectively.

利用60Co-γ射线对设计的GaAs基HEMT力敏结构进行了不同剂量的辐照,通过对辐照前后结构的电学特性、力敏特性分析对比,得到了γ辐照对力敏结构的损伤影响.与未辐照样品相比,90 MRad剂量辐照后HEMT力敏结构的漏极电流降低了约74％,辐照剂量高于100 MRad时,样品被击穿,失去工作特性.力敏特性测试结果表明,随着辐照剂量的不断增加,结构的灵敏度发生降低,90 MRad剂量辐照后结构的灵敏度降低了76％.