微型螺旋感應線圈之開發，以於細胞培養、低功耗電磁致動與家用電器電力感測之應用

Abstract

隨著科技的迅速發展，微型化是近幾十年來的主要趨勢，由於CMOS製程技術持續不斷更新與縮小尺寸，具備無線通訊能力與自然環境條件或生理信號即時監測等多樣化功能的智慧型手持裝置已成為我們未來生活中最便利的工具。相較於CMOS製程技術，微機電系統（MEMS）技術藉由一個微型三維結構來提供多元化的感測及致動機制，已被認可為用來開發下一世代普及的傳感器關鍵技術之一。這項技術已被廣泛應用在電子、機械、光學、聲學、化學和生醫等系統，例如在汽車工業與消費電子產業裡著名的MEMS壓力感測器，慣性感測器和麥克風等等。而現今，感應線圈的應用在我們的生活周遭無處不在，舉凡電廠和變電站裡大至好幾層樓高的變壓器，或是在小至消費型電子元件中的CMOS晶片上的射頻微型螺旋電感等皆有其蹤影。故本論文的目的，旨在展現和延伸微型線圈在生物科技，聲學和電力監控等微系統的應用，用以改善我們的生活。在本論文中，首先發展出一項微型磁場平台技術，配合其實驗結果，可用來快速研究和分析局域化極低頻（ELF）電磁場（EMF）對活體細胞的生物效應。此具備生物相容性的微型平台，係利用玻璃上的感應線圈陣列在微觀尺度下產生局域化極低頻電磁場，透過實驗可觀察到局域化極低頻電磁場對活體細胞的鄰近效應。細胞在60 Hz的磁場暴露下進行培養，其線圈產生的磁場強度設計，製造和運作為1.2±0.1 mT。經過72小時的極低頻電磁場暴露，HeLa（人類子宮頸癌）細胞和PC-12（大鼠嗜鉻細胞瘤）細胞各自表現出約18.4％和12.9％的細胞增殖率減少。此外根據所提出的動態模型，這些細胞增殖的變化，可以歸因於細胞中的訊號轉導過程被磁場感應產生之切向電流所造成的影響。 另外，本論文也針對低功耗電磁式微型揚聲器的製作，提出了一種功率最佳化的銅鎳奈米複合線圈，藉著在奈米複合材料合成之電阻率及導磁率中取得平衡以達到低功耗的目的。在相同的微型揚聲器設計下，添加2克/升奈米鎳粉末的無氰鹼銅電鍍液中所製備之線寬200 μm的複合線圈與無添加之純銅電鍍液下所製備之線圈相比，在揚聲器1至6 kHz的工作頻率範圍內可以節省約40%的功率。此外，聚二甲基矽氧烷(PDMS)薄膜也被利用來製作低功耗毫瓦級電磁式喇叭。在1.76 mW的功率輸入下，一個直徑3.5 mm厚度3.3 µm的振膜可以在2 c.c.的空間內產生頻率1 kHz、聲壓級106分貝的聲音。 在本論文的最後一個部分，提出了一個應用於家用電器雙線式電線電流感測之軟性感應線圈標籤。標籤的製作採用相容於CMOS製程的可撓式SU-8技術，提供了低成本、可靠與普及性高等獨一無二的元件特性。在面積0.5 x 1 mm2內的30匝線圈設計下，此線圈標籤可以對50和60 Hz的輸入電流安培數提供分別約18 μV/ A和21 μV/ A的靈敏度。此外，透過整合電壓感測器的部分，本論文提出了一個具備良好貼附效果並可準確偵測配備標準雙芯電線之家用電器功率的軟性非侵入式功率感測器標籤。在面積0.5x1 mm2內，將50匝線圈之電流感測器和由兩個電容式電極組成的電壓感測器同時製作在100 μm厚的軟性聚對苯二甲酸乙二酯(PET)基板上作為一個感測器標籤。此標籤連接一個主動式低通濾波器電路，可對各自對60 Hz電流和電壓感測提供271.6 mV/A和0.38 mV/V的靈敏度。同時，本論文也藉由提出一個補償電路設計，透過導入電壓感測器訊號至電流感測器中，來解決電流感測器中來自電源線的電壓負載造成之電場耦合干擾，使此電流感測器在量測1 A，60 Hz電流的電力線上可以達到超過40 dB的訊噪比。 另外，本論文也提出一個用來增強此檢測家用雙線式電力線電流之軟性感應線圈標籤靈敏度的設計。實驗結果證明，藉由導入一個磁性C字型夾鉗條紋設計，可以引導和集中感應線圈中心區域的磁通量，得到一個較大的感應電動勢。對一個30匝的感應線圈設計，結合長14.5 mm與貼附於線圈上有約20 μm高的2 µm厚之鎳和鎳鐵C字型夾鉗條紋，在量測1 A，60 Hz電流的SPT-2 16AWG電源線上可分別得到15.5％和37.2％的靈敏度提升。 最後，我們相信本論文所提出之微型線圈設計和製作方法，加上其理論分析模型，在生物系統中的磁場對細胞培養的影響研究、聲學系統的低功率電磁致動，以及家用電器的電力感測上具有極大的應用潛力。

With the rapid evolution of science and technology, miniaturization is the major development trend in recent decades. As the CMOS technology continues scaling, smart hand-held devices combined with the capabilities of wireless communication and varieties of sensing functions for real-time monitoring of the natural environment conditions or physiological signals become the most convenient and powerful tool in our future life. Instead of CMOS technology, micro-electro-mechanical systems (MEMS) technology has been recognized one of the key technologies for developing pervasive transducers by realizing a microscale 3D structure to provide various sensing and actuating functionalities in next generation. It has been widely applied in electrical, mechanical, optical, acoustic, chemical, biomedical system,…etc., such as the well-known MEMS pressure sensors, inertial sensors and microphones in the automotive and consumer electronic industry. Nowadays, inductive coils have been applied everywhere in our environment, like the transformer with several floors high at the power plant and the substation, and small on-chip spiral inductors inside the CMOS chips in consumer electronics. The objectives of this dissertation are aimed to demonstrate and extend the microcoil applications in biotechnology, acoustic and electricity monitoring systems for the improvement of our life. In this dissertation, a platform technology with experimental results has been developed and utilized to rapidly investigate and analyze the biological effects of localized extremely low frequency (ELF) electromagnetic field (EMF) on living cells. The proximity effect of the localized ELF-EMF on living cells is revealed using the bio-compatible microplatform on which an on-glass inductive coil array, the source of the localized ELF-EMF in micro scale, is designed, fabricated and operated with a field strength of 1.2 ± 0.1 mT at 60 Hz for cell culturing study. After a 72 h ELF-EMF exposure, HeLa (human cervical cancer) and PC-12 (rat pheochromocytoma) cells exhibit about 18.4% and 12.9% cell proliferation rate reduction, respectively. Furthermore, according to the presented dynamic model, the reduction of the proliferation can be attributed to the interference of signal transduction processes due to the tangential currents induced around the cells. In addition, this dissertation also presents an optimized Cu-Ni nanocomposite coil synthesized based on the trade-off of resistivity and permeability of the nanocomposite for low-power electromagnetic microspeaker fabrication. A 200μm wide composite coil plated in an alkaline noncyanide copper based bath that is added with 2g/L of Ni nanopowders can realize ~40% power saving of the speaker performed in a frequency range of 1 to 6kHz as compared with the coil made of pure Cu for the same speaker design. In addition, a PDMS membrane is employed for the low-power milliwatt electromagnetic microspeaker fabrication. For a 1.76 mW power input, the speaker with a 3.5 mm in diameter and 3.3 µm thick membrane can generate a sound with the sound pressure level (SPL) of 106 dB @1 kHz in a 2 c.c. coupler. In the last part of this dissertation, a flexible inductive coil tag is presented to sense the electric current in the two-wire power cords of household goods. The tag is fabricated using a CMOS compatible SU-8 flexible technology which provides unique device characteristics of low-cost, reliable, and pervasive. With a 30-turns coil design in an area of 0.5 x 1 cm2, the coil tag can provide a sensitivity of 18 µV/A and 21 µV/A for detecting 50 and 60 Hz electric current in the ampere regime, respectively. Moreover, by integrating with the voltage sensor part, a flexible non-intrusive power sensor tag with good proximity is presented for accurate power detection of the household appliances using typical zip-cord power lines. Both current and voltage sensors with the design of a 50-turns inductive coil and two capacitive electrodes, respectively, in an area of 1.3 x 1 cm2 are fabricated on a 100 μm-thick flexible PET substrate as a sensor tag. The tag exhibits a sensitivity of 271.6 mV/A and 0.38 mV/V via active low-pass filter circuits for the current and voltage detection. Meanwhile, a compensation circuit inputted with the signals of voltage sensor signals is proposed for the interference reduction of in the current sensor that will be electrically coupled from the power cord, so that the current sensor can achieve over 40dB signal-to-noise ratio for measuring the loaded current of 1A, 60Hz on the power line. Furthermore, a sensitivity enhancement scheme is presented for the flexible inductive coil tag used for the current detection of household two-wire power lines. Experimental results show that the inductive coil tag can exhibit a larger induced voltage by the introduction of the magnetic C-clamp stripes that can guide and concentrate the magnetic flux in the center area of the inductive coil. For a 30-turns inductive coil, the incorporation of a 2 μm thick Ni and NiFe C-clamp stripes with 14.5 mm in length and ~20μm in height onto the coil can provide 15.5% and 37.2% sensitivity enhancement, respectively, for detecting 1 A, 60 Hz electric current flow in a SPT-2 16AWG power line. At final, it’s our belief that the proposed coil designs and fabrication processes combined with the theoretical modeling have great potential for the applications of magnetic field investigation of cell culturing in biological system, low power electromagnetic actuation in acoustic system, and electricity monitoring of household appliances.