电场调控射流沉积设备的研制及应用

DEVELOPMENT AND APPLICATION OF ELECTRIC FIELD CONTROL JET DEPOSITION EQUIPMENT

岳泉

11930205

硕士

材料工程

王太宏

2021-05-23

2021-05-23

南方科技大学

深圳

电流体动力（EHD）喷射技术作为一种制备纳米纤维的方式，以其装置构成简单，成本低廉，容易实现，广泛应用于电子、生物医学、催化、过滤和防护等领域。但是，由于电流体动力喷射过程中射流的不稳定运动，抑制了其进一步的发展和应用。本研究课题通过采用电场调控的方式实现射流的聚焦和偏转运动控制，最终达到射流可控沉积的目的，并应用到传感器的制备。射流的聚焦是通过在EHD射流喷射过程中收集板施加负压，引入辅助电极，构建聚焦电场，实现对射流的约束聚焦。本研究中，引入金属圆环辅助电极，金属圆环施加9kV电压可以实现对射流的充分聚焦，射流不稳定运动问题得到有效解决；引入金属板辅助电极，金属板与喷头接触，形成等电位（5kV），也可以充分抑制射流的不稳定运动，得到单束稳定射流。电流体动力喷射过程中设置的流量会影响射流沉积区域宽度，实验结果表明流量为0.2ml/h时，射流沉积区域宽度达到最小，约13.7μm。射流的偏转运动控制是在单束稳定射流运动区域构造偏转电场，带电射流在电场力作用下发生偏转运动。实验结果表明，射流偏转沉积区域宽度随着偏转电场强度增加而增大，而偏转频率的增加则会造成射流偏转沉积区域减小；当偏转电场强度达到240kV/m时，射流被充分拉直，通过实验也实现了规则方格图案的沉积。利用电场调控射流沉积的方式制备取向排列的TPU纤维膜在传感器中得到应用，所设计的电容式压力传感器包含以PDMS为上下基底的齿形结构层， TPU取向纤维膜层及 PVDF-HFP混合LiTFSI制备的聚电解质膜层。传感器受到压力时，齿形结构相互靠近，纤维受到拉伸作用，直径变小。由于纤维直径收缩，纤维之间产生间隙，齿形结构顶部通过TPU纤维之间的空隙与聚电解质膜接触形成双电层，从而使电容能有较大的变化，得到较高的灵敏度。制备的电容式压力传感器在低压段（0-1.1kPa）的灵敏度为42.64kPa-1，中高压段（1.1kPa-100kPa）有较好的线性度，灵敏度约为230.10kPa-1。2000次循环测试后，传感器在低压段（0-1.1kPa）的灵敏度有所增大，约为59.84kPa-1；在中高压段（1.1kPa-100kPa）的灵敏度有所下降，约为179.07kPa-1。同时，测试了传感器对微小物体的响应，传感器上每增加一粒绿豆，电容相对变化量的值变化约为0.023。并将传感器应用于手腕部脉搏波的测量，可以检测到微弱的脉搏波特征信号。

As a method of preparing nanofibers, Electrohydrodynamic(EHD) jetting technology is widely used in the fields of electronics, biomedicine, catalysis, filtration and protection due to its simple device structure, low cost and easy realization. However, due to the unsteady motion of the jet, its further development and application are limited In this study, the focus and deflection of the jet are controlled by using the electric field control method, so as to achieve the goal of controllable deposition of the jet, and applied to the preparation of the sensor.The jet focusing is realized by applying negative pressure to the collecting plate and introducing auxiliary electrode to construct focusing electric field in the process of EHD jet. In the experiment, the 9kV voltage applied to the metal ring auxiliary electrode can realize the full focus of the jet and the unstable motion of the jet can be effectively solved. The metal plate auxiliary electrode is introduced, and the metal plate contacts with the nozzle to form an equipotential (5kV), which can also fully suppress the unstable movement of the jet and obtain a single stable jet. The flow rate set during the electrohydrodynamic jet process will affect the width of the jet deposition area. The experimental results show that when the flow rate is 0.2ml/h, the width of the jet deposition area reaches the minimum, about 13.7μm.The control of the deflection movement of the jet is to construct a deflection electric field in the movement area of ​​a single stable jet, and the charged jet will deflect under the action of the electric field force. The experimental results show that the width of the jet deflection deposition area increases with the increase of the deflection electric field intensity, while the increase of the deflection frequency will cause the jet deflection deposition area to decrease. When the deflection electric field intensity reaches 240 kV/m, the jet is fully straightened, and the regular grid pattern deposition is also realized.Oriented TPU fiber film was prepared by electric field controlled jet deposition and applied in the sensor. The designed capacitive pressure sensor consists of tooth structure layer with PDMS as upper and lower substrate, TPU oriented fiber film and polyelectrolyte film prepared by PVDF-HFP mixed LiTFSI. When the sensor is under pressure, the tooth structures are close to each other, the fiber is stretched, and the diameter becomes smaller. Due to the shrinkage of the fiber diameter, the gap between the fibers is generated, and the top of the toothed structure contacts with the polyelectrolyte film through the gap between the TPU fibers to form an electric double layer, so that the capacitance can be greatly changed and the higher sensitivity can be obtained. The prepared capacitive pressure sensor has a sensitivity of 42.64kPa-1 in the low-pressure section (0-1.1kPa), and a good linearity in the medium-high-pressure section (1.1kPa-100kPa), and the sensitivity is about 230.10kPa-1. After 2000 cycles test, the sensitivity of the sensor in the low pressure section (0-1.1kPa) has increased, about 59.84kPa-1; the sensitivity of the sensor in the medium and high pressure section (1.1kPa-100kPa) has decreased, about 179.07kPa-1. At the same time, the response of the sensor to tiny objects was tested. For every mung bean added to the sensor, the relative change in capacitance ∆C/C0 changes about 0.023. And the sensor is applied to the measurement of the pulse wave of the wrist, and the weak characteristic signal of the pulse wave can be detected.

电流体动力学 电场调控 射流聚焦 射流偏转控制 传感器应用

electrohydrodynamic electric field control jet focusing jet deflection sensor application

中文

独立培养

南方科技大学

岳泉. 电场调控射流沉积设备的研制及应用[D]. 深圳. 南方科技大学,2021.