本研究以閉迴路之馬達控制，控制近場靜電紡絲(NFEF)之滾筒收集器，製作聚偏二氟乙烯(PVDF)之壓電纖維。紡製而成的PVDF壓電纖維，進行拍打測試，藉由低頻率頻率振動的機械能，轉變為電能產生電壓電流的訊號。PVDF壓電纖維具有優越的電壓反應與可撓性，因此可以作為智慧布之類的可撓性感測元件。為了取得更良好的製造程序, 以有利於得到穩定的電能轉換，得到更高的電性訊號，我們利用閉迴路速度控制來改善開迴路系統無補償的問題。藉由閉迴路速度控制，暫態響應和穩態響應可以被精確執行。18%wt PVDF混合溶液放在金屬針筒之中使用直徑0.2、0.25及0.33 mm金屬針; 輸液泵以0.2、0.4及0.8 ml/h 給藥速率進料速率給藥; 13k、15k及17k 高電壓; 針頭與滾筒收集器保持1 mm間距; 針頭以20、160及200 mm/min的速度在滾筒的軸向移動; 滾筒收集器以900-1900 rpm六種不同轉速旋轉。閉迴路速度控制可得到 Ip-p = 8.8×10-7 A (Imax = -5.0 × 10-7 A) 與Vp-p = 0.22V (Vmax = -0.12 V). 開迴路系統可得到Ip-p = 3.2×10-7 A (Imax = -2.1× 10-7 A) 與Vp-p = 0.17 V (Vmax = -0.10 V)。利用閉迴路速度控制所得到之壓電纖維，其電性訊號因而得到改善。用多紡口結構改善滾筒式NFES壓電纖維製程，以製造大面積壓電纖維。以印刷電路板結構與錫球上鑽孔作為噴流口，設計製作多紡口結構。使用田口法設計電場、滾筒收集之速度、加熱溫度與加熱持續時間之製程參數。將PVDF纖維利用掃描式電子顯微鏡(SEM)觀察表面形貌; X光繞射分析儀(XRD)分析PVDF壓電纖維的β相成分特性。用聚二甲基矽氧烷(PDMS)對指叉式電極(IDE)進行封裝。以放電加工製造指叉式電極的模具，在PDMS IDE結構上塗佈銀膠，形成具備導電性的銀膠結構IDE。將PVDF壓電纖維放置於指叉電極之上，封裝成貼片，再施以1400-7000 V電壓，並加熱65°C進行再極化處理，完成智慧貼片製作。

In this study, we report on the closed-loop control for a cylindrical collector to obtain polyvinylidene fluoride (PVDF) piezoelectric fiber using near-field electrospinning (NFES). The as-spun PVDF fibers were laid on the top of parallel electrodes to generate current and voltage signals by means of the energy converting of mechanical energy to electrical energy. The PVDF fibers can be used as a flexible sensing device, such as smart fabric, owing to their excellent voltage response. A PVDF fiber with uniform diameter was expected to have the stable energy conversion for achieving higher electrical current and voltage signals. To ensure the quality of the product process, a closed-loop speed control was designed to improve the disadvantages of open-loop systems. Transient response and steady-state error can be controlled accurately. A mixed solution of 18%wt PVDF was placed into an injector and driven by a syringe pump with 0.2, 0.4, and 0.8 ml/h feeding rates. The needle with 0.2, 0.25, and 0.33 mm diameters was subjected to 13k, 15k, and 17k high voltages with a gap of 1 mm between the needle and the collectors. The travelling speed in the axial direction of the cylindrical collectors at 120, 160, and 200 mm/min, respectively. The cylindrical collector motor operated with six different speeds from 900 to1900 rpm. With the closed-loop speed control, the currents Ip-p = 8.8×10-7 A (Imax = -5.0 × 10-7 A) and the voltages Vp-p = 0.22V (Vmax = -0.12 V) were obtained, which is better than Ip-p = 3.2×10-7 A (Imax = -2.1× 10-7 A) and Vp-p = 0.17 V (Vmax = -0.10 V) with the open-loop system. The PVDF fiber is obtained from closed-loop speed control system, which is better than the fibers of the open-loop system. We improved the NFES using multi-spinnerets with a cylindrical collector to fabricate a large area PVDF fibers. We designed multi-spinnerets by means of printed circuit board (PCB) and drilled spinnerets on the solder balls. The study used Taguchi method to design process parameters, electrical field, collecting velocity of cylindrical collector, heating temperature and heating time. In addition, we used X-ray diffraction (XRD) and scanning electron microscopy (SEM) to analyze β-phase crystal quality and the surface character of PVDF fibers, respectively. In this part, the fibers made a large-area force sensor packaged in a smart patch. The fibers were packaged in polydimethylsiloxane (PDMS) with interdigitated electrode (IDE) structures. The molds of IDE were fabricated by electrical discharge machining (EDM). A conductive silver gel was coated on the IDE by soft contact lithography. The fibers on the IDE were repolarized by the electrical field via high electrical voltage of 1400 to 7000 V and at the temperature of 65°C.

Contents:
List of Figures
List of Tables
Chapter 1: Introduction………………………………………………………………..1
1.1 Background. ……………………………………………………………….1
1.2 Literatures review……………………………….…………………………2
1.3 Motivation………………………………………………………………....7
1.4 Structure of the dissertation………………………………………….……8
Chapter 2: Close-loop Speed Control for PVDF Fibers Manufacturing…..…….....….10
2.1 Materials and methods………………….………..…………...………10
2.1.1 Materials preparation…………………………………………..…..…10
2.1.2 Equipment with closed-loop speed control system………………...…10
2.1.3 Measurement method……………………………...………….………13
2.1.4 Measurement equipment of tapping system……….…...…..…………13
2.2 Measuring result……...……………….……………………..……………15
2.2.1 Electric properties test by energy harvesting…………...…….....………15
2.2.2 Measurement using oscilloscope…………..........................……………15


Chapter 3: PVDF Fibers manufactured using NFES with Multi-Spinneret Design....22
3.1 Configuration of NFES with multi-spinneret design……...……….22
3.2 Materials and methods……………….……..……………………….23
3.2.1 Conductivity and concentration and of PVDF solution………..……23
3.2.2 The design of multi-spinneret structure…………………….....…….25
3.2.3 Manufacturing of multi-spinneret structure…..…………..…...………27
Chapter 4: Closed-loop Speed Control on PVDF Fibers in Smart Patch ……………29
4.1 Materials and method…………………………………..…………..……29
4.1.1 Material preparedness ……………………...………………….……..29
4.1.2 Experiment method …………………...……………………………...30
4.2 Measurement of piezoelectric fibers…………………..……...………34
4.3 PVDF fibers packaged into PDMS smart patch……….…….…….…36
Chapter 5: Result and Discussion………...………………………………...…………38
5.1 Closed-loop speed control and open-loop system in NFES…...…………38
5.1.1 Properties and characteristics of PVDF fiber …...……...……………..38
5.2 PVDF Fibers manufactured using NFES with multi-Spinneret design....44

5.2.1 Influence of electrical field………………………….….………....…..44
5.2.2 Taguchi method analysis…………………………….…….……....…..44
5.2.3 The effect of solder balls dimensions………………...…..……..…..….51
5.2.4 Parameter contribution degree……………………………………....…..52
5.2.5 Beating test…………………..……………….………...…………....…..53
5.3 Closed-loop Speed control on PVDF fibers in smart patch…..….………54
5.3.1 Relationship between PVDF solution parameters and NFES process with closed-loop control…………………………………………….………………54
5.3.2 Properties of PVDF fibers ……………………………….……………63
5.3.3 Repolarization treatment………………………………..………………64
Chapter 6: Conclusions……………………….……………………..…………………64
6.1 Conclusions of the study…………………….…………...………………66
6.2 Future work…………………………………….……...…………………68

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