經(jīng)過長達(dá)6年的毫米級(jí)醫(yī)療植入物研究，美國斯坦福大學(xué)(Stanford University)電子工程系助理教授Ada Poon終于取得符合安全兼容性實(shí)驗(yàn)室的驗(yàn)證報(bào)告，并證實(shí)她的這項(xiàng)研究具有商用化潛力。 Poon興奮地解釋，這項(xiàng)研究主要利用活體動(dòng)物組織作為媒介，可在大約5公分以上的距離透過“中場”(mid-field)無線電源提供超過200微瓦的功率。 “我們確定模擬過程相當(dāng)安全，”Poon指出，”我們使輸出功率保持在500mW，這和手機(jī)是一樣的，接著我們進(jìn)行測量，檢查溫度的上升。我們進(jìn)行一切的驗(yàn)證，最終才真的確定與證明這項(xiàng)技術(shù)是安全的，然后我們才送交第三方測試?！? Poon和其他研究人員們針對(duì)這項(xiàng)主題為“醫(yī)療植入設(shè)備的中場無線電源研究”提交了一份論文至國家科學(xué)院(National Academy of Sciences)，內(nèi)容描述一種可穿透約5cm皮膚組織為植入于兔子心臟中的2mm微型刺激器供電的方式。 這種電流感應(yīng)耦合方法取決于植入設(shè)備與外部設(shè)備之間的近場耦合──在植入設(shè)備與外部設(shè)備之間無非就是一層薄薄的皮膚。Poon的團(tuán)隊(duì)采取了一種不同的方法，經(jīng)由生物組織擁抱1.6GHz的信號(hào)傳輸，而非采取試圖避開的作法。 斯坦福大學(xué)的研究人員們稱這種方式為“中場”(mid-field)無線。斯坦福大學(xué)研究生John Ho解釋，基本上是將“近場”轉(zhuǎn)換為“遠(yuǎn)場”(far-field)電磁波，這種傳輸方式較安全但遠(yuǎn)離訊號(hào)源后快速衰減，但已能將能量傳送到更遠(yuǎn)的距離。 該技術(shù)可傳送超過200mW功率，遠(yuǎn)遠(yuǎn)超過當(dāng)今起搏器所需的8mW功耗。Poon以及其他研究人員們預(yù)見到有一天將出現(xiàn)一種僅有米粒大小的微型刺激器，它可能比當(dāng)今所用的植入設(shè)備或藥物更加高效。 “我們的供電方式適用于更廣泛的設(shè)備類型，如植入式診斷傳感器或局部藥物遞送工具，”Ho說，“這些設(shè)備未能商業(yè)化開發(fā)出來的部份原因可能是現(xiàn)有植入設(shè)備尺寸太大?！? “一個(gè)有趣的應(yīng)用是在一種俗稱‘電藥’(electroceutical)的新興藥物治療方式，這種直接安裝在人體內(nèi)部進(jìn)行調(diào)節(jié)的微型設(shè)備，在某些疾病的治療上可能比用藥物更有效。在這方面還需要更多的研究，才能了解疾病的神經(jīng)基礎(chǔ)以及開發(fā)電子治療方法，但無論如何，所有的這一類途徑都需要安全傳送電力的方式。”

斯坦福大學(xué)開發(fā)的微型刺激器植入設(shè)備尺寸約2mm，大約是一顆米粒的大小。
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本文授權(quán)編譯自EE Times，版權(quán)所有，謝絕轉(zhuǎn)載 本文下一頁：從物理到醫(yī)學(xué)，從理論到手術(shù)

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• 無線充電標(biāo)準(zhǔn)比拼，市場期待大一統(tǒng)Xc6esmc

{pagination} 從理論到手術(shù) 為了使植入式設(shè)備最小化，許多微型刺激器并未加裝電池。當(dāng)使用者想產(chǎn)生脈沖以減輕疼痛或讀取嵌入式傳感器的數(shù)據(jù)時(shí)，他們通常都必須在患處放置一個(gè)如信用卡大小的充電器。其他的刺激或傳感器可能內(nèi)建微型電池，從而實(shí)現(xiàn)自動(dòng)化作業(yè)。但用戶仍必須經(jīng)由外部設(shè)備為植入式設(shè)備進(jìn)行充電。 而在未來的12個(gè)月內(nèi)，預(yù)計(jì)Poon的研究團(tuán)隊(duì)就能首次在人體內(nèi)植入這種新式微型刺激器，可能用于治療外圍神經(jīng)疼痛。不過，在這項(xiàng)產(chǎn)品獲準(zhǔn)用于醫(yī)療用途以前，大約還要經(jīng)過幾年的時(shí)間進(jìn)行測試。

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Poon 所開發(fā)的設(shè)備比目前由Medtronic與St. Jude Medical等公司開發(fā)約幾公分大小的起搏器更小幾個(gè)數(shù)量級(jí)。這些較大型設(shè)備的問題是必須抗拒更大的力量，才能保持與身體組織之間的恒定。此 外，Poon也有興趣探索這種電磁能量究竟可達(dá)到多遠(yuǎn)的距離限制。

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“我所受的訓(xùn)練主要是在信息論方面，”她說，“這是在電子工程學(xué)中最密集使用數(shù)學(xué)的部份，我們總是問這樣的問題：通過一定信道的最高數(shù)據(jù)速率是多少？” 她的職業(yè)生涯一開始是在英特爾(Intel)公司從事可重配置射頻方面的工作，目前在于制造出更高靈敏度的基帶芯片。后來，她還曾經(jīng)任職SiBeam，該公司是60GHz CMOS 芯片先驅(qū)，為消費(fèi)電子設(shè)備提供高解析的無線視頻。 “當(dāng)我開始研究生物組織的電磁學(xué)時(shí)，我對(duì)于這方面所存在的限制也感到好奇。每個(gè)人都在用電感耦合，但什么是最佳解決方案卻一直沒有答案?！? 在經(jīng)過長達(dá)6年的追尋后，這個(gè)問題仍然開放各種解答，未來，也還有更多年的路要走。她說，“這是一段漫長的旅程?！? “這項(xiàng)研究的一個(gè)有趣之處在于它所涵蓋的范圍是如此地廣泛，從物理到醫(yī)學(xué)，”Ho說，“有一段時(shí)間我還同時(shí)展開數(shù)學(xué)研究與動(dòng)物實(shí)驗(yàn)──這真的很令人振奮！” 微型刺激器可經(jīng)由導(dǎo)管插入體內(nèi)。 本文授權(quán)編譯自EE Times，版權(quán)所有，謝絕轉(zhuǎn)載 編譯：Susan Hong 參考英文原文：Implant Gets Power Through Flesh，by Rick Merritt

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• 無線充電標(biāo)準(zhǔn)比拼，市場期待大一統(tǒng)Xc6esmc

{pagination} Implant Gets Power Through Flesh Rick Merritt SAN JOSE, Calif. — Ada Poon still recalls the day she read the report from the safety compliance lab. The Stanford assistant professor had gotten validation for her six years of research on millimeter-scale medical implants that were now shown to have commercial potential. "I was quite excited," says Poon of her work exploiting living animal tissue as a medium to deliver more than 200 microwatts of power over a distance of 5 centimeters or more. "We knew it was safe in simulation," Poon tells us. "We kept the output power to 500 mW, which is the same as a cellphone, and we did measurements to check the temperature rise. We did all this validation, but in the end to be really sure and articulate our point that our technique was safe, I said let's do third-party testing." Today Poon and colleagues submitted a paper to the National Academy of Sciences on their work in so-called midfield wireless power for a medical implant. It describes a way to deliver power through nearly 5 cm of tissue to a 2 mm microstimulator implanted on a rabbit's heart. Current inductive coupling methods rely on near-field coupling between an implant and an external device with nothing more than a thin layer of skin in between. Poon's team took a different approach, embracing propagation of the 1.6 GHz signal through biological tissue rather than trying to avoid it. The Stanford researchers call their approach "mid-field" wireless. Essentially, they converted "electromagnetic waves from the 'evanescent' or 'near-field' type, which are safe but decay rapidly away from the source, to the 'propagating' or 'far-field' type, which carry energy away with much farther reach," explains John Ho, a Stanford graduate student and co-author of the paper The more than 200 microwatts the technique delivers far exceeds the 8 mW consumed by today's pacemakers. Poon and others foresee the advent of a class of microstimulators the size of a grain of rice that may someday be more effective for some ailments than today's implants or drugs. "Our powering method could be applicable to a broader class of devices that have yet to be developed, such as implantable diagnostic sensors or localized drug delivery tools," says Ho. "Part of the reason they are not commercially used today may be because of the bulkiness of existing implants. "One intriguing application is in an emerging class of medicines called 'electroceuticals.' Tiny devices that directly modulate neural activity in the body may provide more effective treatments for some disorders than drugs. Much more research is required to understand the neural basis for diseases and develop electronic treatments, but all such approaches will require ways to safely transfer power." The Stanford microstimulator implant measures 2mm across, about the size of a grain of rice. To keep the implants small, many microstimulators will have no battery. When users want to generate pulses to relieve pain or read data from an embedded sensor, they will place over the affected area a credit-card sized charger, such as the thin 6x6 cm device the Stanford team used. Other stimulators or sensors may have tiny batteries so they can work automatically. Users will charge the implants with the external device. Within the next 12 months, Poon's team hopes to implant its microstimulator in a human for the first time, probably on peripheral nerves for pain therapy. It could take several years of tests before such products are approved for medical use. Poon's device is an order of magnitude smaller than today's centimeter-sized pacemakers from Medtronic and St. Jude Medical. The larger devices must resist greater forces to stay anchored to tissues amid the flow of body fluids. Poon is interested in exploring the limits of what electromagnetic energy can deliver over how great a distance. "My training is in information theory," she says. "It's one of the most mathematically intensive branches in electrical engineering. We always ask the question: What's the highest data rate through a given channel?" Her career started with work on reconfigurable radio at Intel, trying to make baseband chips as agile as possible. She later worked at SiBeam, which pioneered 60 GHz chips in CMOS, delivering wireless, high-definition video for consumer electronics gear. "When I started work on electromagnetics in biological tissue, I applied the same curiosity about what's the limit. Everyone was using inductive coupling, but what was the optimal solution was not answered." The question remains an open one she has now been pursuing six years, with several more years of work ahead. "It's a long journey," says Poon. "One interesting thing about this work was that it was incredibly broad, ranging from physics to medicine," says Ho. "There were times where I performed mathematical studies and animal experiments on the same day -- as primarily a theorist by training, this was exhilarating/" The microstimulator could be inserted via a catheter.