通信單片機外文翻譯.doc

一個完全植入式無線壓力監(jiān)測系統(tǒng)的開發(fā)摘要：一個完全植入式無線壓力傳感器監(jiān)測系統(tǒng)的開發(fā)是為了檢測體內(nèi)膀胱的壓力。該系統(tǒng)包括一個小型的商業(yè)壓力模具經(jīng)導(dǎo)管連接到電子放大設(shè)備，一個微控制器，無線發(fā)射器，電池和個人數(shù)字助理（PDA）或接收無線數(shù)據(jù)的計算機。該傳感器是完全植入的，并且每秒傳送一次壓力數(shù)據(jù)，壓力檢測評估范圍為1.5 psi，分辨率為0.02 psi。在體外，設(shè)備的校準(zhǔn)測量表現(xiàn)出高度的線性度和良好的時間響應(yīng)。該裝置植入一些豬的體內(nèi)進(jìn)行研究，歷時超過3天。該系統(tǒng)能適用于其他方面的壓力讀數(shù)，以及其他生命體征的測量，它邁出了一個無處不在的發(fā)展遠(yuǎn)程醫(yī)療和遠(yuǎn)程病人監(jiān)控平臺的第一步。關(guān)鍵詞：微機電系統(tǒng)、壓力傳感器、植入、患者的監(jiān)測、遙測、遠(yuǎn)程醫(yī)療、膀胱、無線1介紹：目前，醫(yī)學(xué)界對在家和在醫(yī)院的病人的遠(yuǎn)程醫(yī)療和遠(yuǎn)程監(jiān)控產(chǎn)生了濃厚的興趣。當(dāng)前，病人監(jiān)護(hù)儀器和實現(xiàn)手法是繁瑣和局限的。例如，在重癥監(jiān)護(hù)病房，血壓監(jiān)測可用動脈線進(jìn)行連續(xù)監(jiān)測。這是一個放置在動脈的導(dǎo)管，并且外部傳感器能檢測到壓力。它的局限性是高度可變的準(zhǔn)確性，患者往往服用鎮(zhèn)靜劑，以防止因運動對自身造成傷害。另一方面，在標(biāo)準(zhǔn)的基礎(chǔ)護(hù)理中，雖然對病人是完全非侵入性，并且免除了他們的負(fù)擔(dān)，但是，病人血壓標(biāo)準(zhǔn)測量與非連續(xù)點的測量通常采取每2-12小時一次。重要的生命體征測量值間的顯影可能被錯過。目前，還沒有連續(xù)監(jiān)測生命體征的，并且可提供無極端入侵和或麻煩的，如同臨床醫(yī)生的設(shè)備。一個連續(xù)的，能夠?qū)崟r檢測的，并且監(jiān)測沒有顯著減少病人的舒適或限制其自身的運動的設(shè)備將在性能和舒適的集約化和標(biāo)準(zhǔn)治療上縮小差距。一個簡單而劃算的的解決辦法是利用無線遙控可植入微系統(tǒng)。無線遙測技術(shù)釋放了被束縛的患者，使他們脫離了大醫(yī)院的監(jiān)控，他們可以參加醫(yī)院無線傳感器網(wǎng)絡(luò)，該網(wǎng)絡(luò)通過最大限度地減少人員的工作負(fù)荷，增加獲得的數(shù)據(jù)量，并簡化其存儲和處理，進(jìn)而可能會提升監(jiān)控效率。在大多數(shù)情況下，無線植入式壓力傳感器發(fā)展的重點是由無線電供電設(shè)備射頻（RF）感應(yīng)，使無限期植入和手術(shù)操作時沒有必要交換電池。此外，設(shè)備總體積最小化，因為電池通常是最大的組成部分。一些團(tuán)體已經(jīng)開發(fā)和測試出能夠檢測股動脈動態(tài)血壓或動物模型主動脈的設(shè)備（納杰菲和Ludomirsky2004； Schlierf等。2007年）。然而，傳輸范圍通常局限于厘米（納杰菲和Ludomirsky2004；Schlierf等。2007）和傳感器射頻感應(yīng)時只能傳輸數(shù)據(jù)。這往往限制了離散時間點的測量或在病人身上裝上天線在所有的時間連續(xù)測量（CardioMEMS2007；沃爾頓和克魯姆 2005年）。這里，我們提出了一個不同的方法來監(jiān)測流動壓力，其中包括：微壓模具，電子放大器，微控制器，無線發(fā)射器，電池，和通訊的個人數(shù)字助理（PDA）或計算機。2方法和材料：壓力傳感平臺分為三個部分：壓力傳感導(dǎo)管導(dǎo)線；傳感器節(jié)點（圖1）；PDA或電腦接收器。以上各部分的制造將在下面部分討論：2.1導(dǎo)管導(dǎo)線：該導(dǎo)管導(dǎo)線裝載了壓力傳感器，并且連接到傳感器節(jié)點上（圖2）。它由一個用紫外線環(huán)氧樹脂（Masterbond UV10）印刷在測量0.650.65毫米的陶瓷印刷電路板（PCB）的壓阻壓力傳感器（硅微5108）構(gòu)成。模具設(shè)計參考了它的大小，感應(yīng)距離，精確度，靈敏度具有1.6 mV/ psi的音頻/視頻。芯片上的應(yīng)變片配置在溫度補償?shù)幕菟沟请姌?。然后，該芯片（西邦?402C）焊接到基板焊盤上。四個單獨絕緣鉑銥（鉑銥），通過一個7.5French（2.5毫米）的電線焊接到連接到接觸焊盤的電路板。紫外線環(huán)氧樹脂應(yīng)用于基板焊盤和芯片上，并進(jìn)行8分鐘固化，以防止任何鉑銥電線或wirebonds破壞連接。有四個楔形孔金帽削減了紫外線對環(huán)氧樹脂印刷電路板壓貼的壓緊膜，以保護(hù)芯片。四鉑銥線被纏繞在一個高強度聚酯絕緣的磁芯，并通過聚乙烯管材。該裝配用硅膠填充焊接螺紋管。圖1圖1：在設(shè)備充分植入并充分包裝后，該壓力傳感器安置在7.5French的導(dǎo)管中，它直接植入膀胱或腹腔。導(dǎo)管的另一端連接到傳感器節(jié)點，這些點由單片機和無線發(fā)射器，電子產(chǎn)品放大器和電池組成。該設(shè)備是包裹在LDPE薄膜上并用醫(yī)用級硅橡膠制造成型。圖2圖2：藝術(shù)家的設(shè)計引領(lǐng)導(dǎo)管導(dǎo)線技術(shù)的尖端。（a）給出了無包裝的領(lǐng)先技術(shù)，商業(yè)壓緊膜焊接到PCB板上。四鉑銥通過導(dǎo)管電線焊接到PCB板上。（b）描繪了包裝的領(lǐng)先技術(shù)。金蓋板，保護(hù)芯片和絲焊。纏鉛玻璃紙; PDMS塑造其周圍，以增加生物的相容性。2.2傳感器節(jié)點：該傳感器節(jié)點由三個部分組成：電子放大器，微控制器和無線發(fā)射器，電池。導(dǎo)管導(dǎo)線的一端焊接到一個特定的電路板上。這個電路板是四元組微功耗，單電源運算放大器（德州儀器TLV2764），一個2.5伏的電壓調(diào)節(jié)器芯片（模擬裝置REF192）和一個單刀雙擲（SPDT）磁簧開關(guān)打開和關(guān)閉設(shè)備（哈姆林）（林2007）。芯片組的電壓調(diào)節(jié)器的電源電壓供電的設(shè)備和其他電子產(chǎn)品電壓設(shè)置到2.5 V。以防止因電池電壓的變化引起壓緊膜信號的變化。運算放大器被配置為無任何偏移量將傳感器電壓從放大橋放大到300倍。生理相關(guān)的壓力測量范圍為1.5 psi的表壓，并與器件的靈敏度，電源電壓和放大器，設(shè)備輸出為1.2伏/ psi和生理壓力范圍為1.8V。該放大電路的輸出被連接到微控制器和無線發(fā)射器（Mica2Dot（Crossbow MPR510CA），以下簡稱為the dot mote），其中發(fā)射功率為433兆赫。我們編程的微控制器以獲取和傳輸數(shù)據(jù)，同時最大限度地提高電池的壽命在以下三個方面：首先，微控制器使傳感器的測量脈沖周期為30微妙，在這之后整個設(shè)備進(jìn)入睡眠模式。第二，測量時只有每秒一次。最后，由于傳輸消耗最大電量，采樣的數(shù)據(jù)存儲在本地the dot mote中，并且每測量30次傳輸一次（林等人。2007）。這些技術(shù)是能量消耗從3兆焦耳降到625J（林2007年，林等人2007年）。電池使用的是3.7伏，850毫安時鋰聚合物電池（電池美國）。該裝置的使用壽命是387300次測量，或者在電池電壓低于電源電壓情況下，大于四天采樣率不變。一旦組裝完成，傳感器節(jié)點包裹25微米厚的低密度聚乙烯（LDPE，塑料薄板供應(yīng)）和壓縮，再PDMS成型。此后，該裝置浸入聚二甲基硅氧烷的第二硅層，以堵塞第一層硅橡膠的任何漏洞。期間和之后的包裝過程中，電池?zé)o法充電或更換，所以是釹磁鐵被堆放在模具上并激活磁性開關(guān)和在它24小時治愈后關(guān)閉設(shè)備。2.3無線通信：該點配有互補的通信接收機基站(Crossbow MIB510CA)，該基站連接到計算機。發(fā)送的dot mote是十六進(jìn)制格式的，其中包括一個時間戳，一個獨特的ID標(biāo)簽，剩余的電池電壓，放大的壓力數(shù)據(jù)。 LabVIEW的（美國國家儀器公司）的程序來讀取和轉(zhuǎn)換成數(shù)據(jù)包，該數(shù)據(jù)包保存在一個文本文件中，并能實時繪制圖形曲線。2.4體外試驗：一旦一個導(dǎo)管導(dǎo)線制作完成，每根導(dǎo)線都要進(jìn)行單獨測試，并且將其放置在密封壓力腔中測試其性能，這是通過壓力腔蓋電連接到電線上。導(dǎo)線外部供電（安捷倫E3630A）和高精度萬用表測試輸出電壓（吉時利2000年）。壓力是在大氣壓力恒定下舉行了30分鐘，而生物醫(yī)學(xué)Microdevices的（2009）NISTcalibrated壓力表（歐米茄DPG5600B-30A）11:259-264261器件的輸出和壓力讀數(shù)每5分鐘記錄一次。體腔連接到了一個壓縮的氮氣瓶，通過壓力調(diào)節(jié)器將壓力上升到1.0 或1.5 psi并保持三十分鐘。對于第一個十分鐘，壓力和電壓讀數(shù)被全部帶走，在后來的二十分鐘，每五分鐘檢測一次。壓力容器釋放出大氣壓力和電壓，前十分鐘，壓力徹底讀出，在后來的二十分鐘，每五分鐘讀取一次。每根導(dǎo)線校準(zhǔn)三次，以測試環(huán)境對導(dǎo)線及其包裝的影響。他在空中檢測，首先作為一個控件，然后導(dǎo)線的尖端放置在容器的燒杯的水中，開始測試之后，讓它在水下保持四天。如果四天后輸出的量值和時間響應(yīng)和以前一樣，這就搭配了一個傳感器節(jié)點。經(jīng)過一個傳感器節(jié)點配對的導(dǎo)管導(dǎo)線，整個裝置進(jìn)行了包裝前的再次測試。導(dǎo)線被放置在密封的水壓力容器。該傳感器節(jié)點連接到連接外部壓力腔的導(dǎo)線，并有電池或者DC電源供電。LabVIEW計算機程序運算和存儲無線壓力數(shù)據(jù)。壓力是從0-1.5psi逐步加大以測試實驗所需壓力范圍，每步保持五分鐘，每兩分鐘進(jìn)行一次壓力讀數(shù)。為了檢驗該設(shè)備分辨率，增量為0.02 psi的壓力變化從0到0.1psi和0.1psi的增量從0.1到1.5psi。在每次試驗結(jié)束后，標(biāo)準(zhǔn)曲線生成相關(guān)的電壓數(shù)值通過電腦記錄到壓力腔內(nèi)。另一個測試封裝設(shè)備是將它淹沒 2.5 gal 染色的水中并傳輸數(shù)據(jù)，直到電池耗盡。之后進(jìn)行數(shù)據(jù)分析，以尋找任何短路的跡象，描繪任何傳感器漂移現(xiàn)象和量化設(shè)備的全壽命。包裝后來被去除，看是否有漏水的痕跡。2.5 體內(nèi)測試：經(jīng)加州大學(xué)洛杉磯分校醫(yī)學(xué)中心 IRB # 2004年-185-11批準(zhǔn)，成年母豬被用于作為體內(nèi)測試。一個設(shè)備植入膀胱，另一個放置腹腔內(nèi)作為參考。當(dāng)傳感器節(jié)點被放置在皮下組織中時，導(dǎo)管的導(dǎo)線被放在那些場所。手術(shù)后，豬被關(guān)在動物園的圍欄中，從而使在圍欄外的計算機和設(shè)置好的無線電接收器收集數(shù)據(jù)。在這種情況下，豬都有充分的意識到和動態(tài)。在接下來的 2-4 天，豬被處死，然后分離出設(shè)備。簡單進(jìn)行尸檢，以尋找組織炎癥或任何免疫反應(yīng)的有機硅包裝。然后檢查設(shè)備是否有任何損壞，泄漏或如有必要的話，再尋找任何其它故障點。3結(jié)果及討論：組裝完畢的鉛導(dǎo)線和傳感器節(jié)點的測試顯示了傳感器的快速線性響應(yīng) (1.34 psi/V）。在初次測試之后，對設(shè)備進(jìn)行拆卸和重新組裝。觀察到偏移量略有改變。一旦該設(shè)備完全包裝和準(zhǔn)備植入，這種變化通過計算的壓力校準(zhǔn)的比較曲線和壓力表的實際壓力和調(diào)整校準(zhǔn)曲線的偏移值進(jìn)行補償。在測試聚二甲基硅氧烷包裝的完整性時，設(shè)備在不失靈的情況下運作，直到電池設(shè)備使用107 h而耗盡。在前兩天半時間內(nèi)，輸出的電壓變化小于0.0003。然而，在接下來的 2 天，電壓穩(wěn)步下降直至設(shè)備停止運作。一旦停止運作，設(shè)備就檢測出無液態(tài)水或氣態(tài)水，或水的PDMS滲透層，這樣，數(shù)據(jù)就不會因短路丟失了。4結(jié)論：總之，我們已建立了完全植入體內(nèi)的無線壓力傳感器，其在短期內(nèi)應(yīng)用于泌尿系統(tǒng)的研究和病人監(jiān)護(hù)儀上。體外測試演示其快速的時間響應(yīng)和其高線性。通過膀胱和豬腹腔模型的體內(nèi)試驗，壓力傳感系統(tǒng)能夠成功記錄醫(yī)學(xué)相關(guān)的數(shù)據(jù)，其中包含像排尿這種生理活動。這個平臺可以擴展其他的傳感模式，如測核心溫度的熱敏電阻，白金和銀電極測血液或組織氧氣電壓，鉛植入動脈以獲得心率血壓分析參數(shù)。導(dǎo)管進(jìn)一步小型化到點，這樣，它能放入針中，進(jìn)而可以消除人體對大手術(shù)的需要。為了這次試驗，電子和無線傳輸單元被保存在內(nèi)部，以免動物對其造成損壞。對于人類的應(yīng)用，它更實用的做法是將設(shè)備固定在身體表面。在醫(yī)院中，像它這樣，傳感器平臺的發(fā)展將會更加實際和普遍。附件2：外文原文This article comes from：Biomed Microdevices (2009) 11:259264DOI 10.1007/s10544-008-9232-1Development of a fully implantable wireless pressuremonitoring systemAbstract： A fully implantable wireless pressure sensor system was developed to monitor bladder pressures in vivo. The system comprises a small commercial pressure die connected via catheter to amplifying electronics, a microcontroller, wireless transmitter, battery, and a personal digital assistant (PDA) or computer to receive the wireless data. The sensor is fully implantable and transmits pressure data once every second with a pressure detection range of 1.5 psi gauge and a resolution of 0.02 psi. In vitro calibration measurements of the device showed a high degree of linearity and excellent temporal response. The implanted device perfored continuously in vivo in several porcine studies lasting over 3 days. This system can be adapted for other pressure readings, as well as other vital sign measurements; it represents the first step in developing a ubiquitous sensing platform for telemedicine and remote patient monitoring.Keywords： MEMS . Pressure sensor . Implantable . Patient monitoring . Telemetry . Telemedicine . Bladder .Wireless1 IntroductionThere has been significant interest in the medical community in telemedicine and remote patient monitoring at home and in the hospital . Current patient monitoring instrumentation and practices can be cumbersome and restrictive. For example, in the intensive care unit, blood pressure monitoring can be monitored continuously with an arterial line. This is a catheter that is placed in the artery, and an external transducer detects the pressure. The limitations of this are that the accuracy is highly variable, and the patient is often sedated to prevent him from injuring himself from movement. On the other hand, in standard floor care, while completely non-invasive and burden-free to the patient, standard blood pressure measurements with a cuff are non-continuous point measurements typically taken every 212 h. The development of critical vital signs between measurements could be missed. Currently, there is no device which provides clinicians with continuous monitoring of vital signs without being extremely invasive and/or cumbersome.A device capable of continuous and real time measurement and monitoring without significantly reducing the patients comfort or restricting his movement would fill the gaps in performance and comfort between intensive and standard care. A simple and cost effective solution is to utilize implantable microsystems utilizing wireless telemetry. Wireless telemetry frees the patient from being tethered to large hospital monitors and can participate in a hospital sensor network, which could increase monitoring efficiency by minimizing staff work load, increasing the amount of data obtained, and streamlining its storage and processing.For the most part, wireless implantable pressure sensor development has focused on devices powered by radio frequency (RF) induction, which enables indefinite implantation and operation without the need for subsequent surgeries to exchange batteries. Also, the total device volume is minimized, as the battery is typically the largest component. Several groups have developed and tested devices that detect dynamic blood pressure in the femoral artery or aorta of animal models (Najafi and Ludomirsky 2004; Schlierf et al. 2007). However the transmission range is often limited to centimeters (Najafi and Ludomirsky 2004; Schlierf et al. 2007) and the sensor can only transmit data when it is exposed to RF energy. This often limits the measurements to discrete points in time or tethers the patient to an antenna at all times for continuous measurements (CardioMEMS 2007; Walton and Krum 2005).Here we present a different approach to monitor ambulatory pressures, which consists of a micromachined pressure die, amplifying electronics, microcontroller, wireless transmitter, and battery, and communicates with a personal digital assistant (PDA) or computer.2 Methods and materialsThe pressure sensing platform is divided into three parts: the pressure sensing catheter lead, the sensor node (Fig. 1), and the PDA or computer receiver. The fabrication of each of these parts is discussed below:2.1 Catheter leadThe catheter lead houses the pressure sensor and connects it to the sensor node (Fig. 2). It consists of a piezoresistive pressure sensor (Silicon Microstructures 5108) measuring 0.650.65 mm affixed onto a ceramic printed circuit board (PCB) with UV epoxy (Masterbond UV10). The die was chosen for its size, sensing range, and precision, with a sensitivity of 1.6 mV/psi/V. The strain gauges on the die are configured in a temperature-compensated Wheatstone bridge. The chip was then wirebonded (West Bond 7402C) to contact pads on the substrate board. Fourindividually insulated platinumiridium (PtIr) wires threaded through a 7.5 French (2.5 mm) catheter were soldered to leads on the board connected to the contact pads. UV epoxy was applied over all contact and solder pads on the substrate board and chip and cured for 8 min to prevent any of the PtIr wires or wirebonds from breaking contact. A gold cap with four wedge-shaped holes cut out of the side was affixed with UV epoxy onto the PCB over the pressure die to protect the chip. The four PtIr wires were wound around a high-tensile insulating polyester core and threaded through tygon tubing. This assembly was threaded through silicone tubing prior to soldering.Fig. 1 The implanted device after fully being fully packaged. The pressure sensor is housed at the end of a 7.5 French catheter, which is implanted directly into the bladder or peritoneal cavity. The other end of the catheter is connected into the sensor node, which consists of the dot mote (microcontroller and wireless transmitter), the amplifying electronics, and battery. The device is wrapped in LDPE film and molded in medical-grade PDMS.Fig. 2 Artists rendition of catheter lead tip. (a) Shows the lead tip unpackaged. A commercial pressure die is affixed and wirebonded onto a PCB substrate. Four PtIr wires fed through the catheter are soldered onto the PCB. (b) Depicts the lead after packaging. A gold lid covers and protects the chip and wirebonds. Cellophane is wrapped around the lead; PDMS is molded around it to make it biocompatible2.2 Sensor node The sensor node consists of three components: amplifying electronics, microcontroller and wireless transmitter, and the battery. The free end of the catheter lead is soldered onto a custom-designed circuit board. On this circuit board are a quad micro-power, single supply operational amplifier (Texas Instruments TLV2764), a 2.5 V voltage regulator chip (Analog Devices REF192), and a single pole, doublethrow(SPDT) magnetic reed switch to turn the device on and off (Hamlin) (Lin 2007). The voltage regulator chip sets the supply voltage powering the device and other electronics to 2.5 V to prevent any variations in signal from the pressure die due to variations in battery voltage. The operational amplifiers were configured to null any offset from the sensor bridge and amplify the bridge voltage by a factor of 300. The physiologically-relevant pressure measurement range was 1.5 psi gauge pressure, and with the device sensitivity, supply voltage, and amplification, the device output was 1.2 V/psi and 1.8 V for the physiological pressure range.The output of the amplifying circuit was connected to the microcontroller and wireless transmitter (Mica2Dot (Crossbow MPR510CA), hereafter referred to as the dot mote), which transmits at 433 MHz. We programmed the microcontroller to acquire and transmit data while maximizing battery life in three ways: first, the microcontroller pulses the sensor for only 30 s each measurement cycle, after which the entire device goes into sleep mode. Second, the measurements are taken only once per second. Finally, since the greatest power draw comes from transmission, the sampled data is stored locally on the dot mote and is transmitted every 30 measurements (Lin et al. 2007). These techniques reduce the energy consumption from 3 mJ per measurement to 625 J (Lin 2007; Lin et al. 2007). The battery used is a 3.7 V, 850 mAH lithium-polymer battery (Batteries America). The device was observed to have a lifetime of 387,300 measurements or 4 days at this sampling rate before the battery voltage dropped below the supply voltage of the device.Once fully fabricated, the sensor node was wrapped in 25m-thick low density polyethylene (LDPE, Plastic Sheeting Supply) and compression-molded in PDMS. Afterwards, the device was dipped into PDMS for a second silicone layer to plug any holes in the first PDMS layer. During and after the packaging process, the battery cannot be charged or replaced, so neodymium magnets were stacked on top of the mold to activate the magnetic switch and turn off the device while it cured for 24 h.2.3 Wireless communicationThe dot mote communicates with a complementary receiver station (Crossbow MIB510CA), which is connected to a computer. The dot mote sends data in a hex format that includes a timestamp, a unique ID tag, the remaining battery voltage, and the amplified pressure data. LabVIEW (National Instruments) was programmed to read and convert the data packets, which are stored in a text file and graphed in real time.2.4 In vitro testsOnce fabrication of each catheter lead was completed, the lead alone was tested and characterized by placing it in a sealed pressure chamber (Binks). It was electrically connected to wires threaded through the lid of the pressure chamber. The lead was externally powered (Agilent E3630A) and the output voltage was read by a high precision multimeter (Keithley 2000). The pressure was held constant at atmospheric pressure for 30 min while the device output and pressure readings from an NISTcalibrated pressure gauge (Omega DPG5600B-30A) were recorded every 5 min. The chamber was connected to a cylinder of compressed nitrogen through a pressure regulator and the pressure was raised in 1.0 or 1.5 psi increments and held for 30 min. For the first 10 min, pressure and voltage readings were taken every minute and every 5 min for the following 20 min. At the conclusion of the calibration, the pressure vessel was vented back to atmospheric pressure and voltage and pressure were read every minute for 10 min and every 5 min for the following 20 min. The calibration was performed three times for each lead to test the effects of the environment on the lead and its packaging. It was tested in air first as a control, and then the tip of the lead was placed in a beaker of water inside the chamber. It was left submerged for 4 days when it was tested again. If the output magnitude and temporal response stayed consistent after the fourth day, it was paired with asensor node.After a sensor node was paired to a catheter lead, the entire device was tested again before packaging. The lead was placed in water within the sealed pressure vessel. The sensor node was connected to the lead outside the pressure chamber and powered either by the battery or DC power source. The LabVIEW program ran on the computer and stored the wireless pressure data. The pressure was incrementally stepped up from 01.5 psi to test the required pressure range and held at each step for 5 min with pressure readings taken every 2 min. To test the resolution of the device, the incremental pressure changes were 0.02 psi from 00.1 psi and 0.1 psi for 0.11.5 psi. At the conclusion of each test, a calibration curve was generated that related the voltage recorded on the computer to the pressure inside the chamber.Another test of the packaged device was performed by submerging it in a 2.5 gal bucket of dyed water and left to transmit data until the battery drained out. Afterwards, the data was analyzed to look for any signs of short circuits, characterize any sensor drift, and quantify the full lifetime of the device. The packaging was later removed to look for any signs of water leakage.2.5 In vivo testsAdult female swine were used for in vivo testing as approved by UCLA Medical Center IRB #2004-185-11. One device was implanted into the bladder and another was placed inside the peritoneal cavity as a reference. The tips of the catheter leads were placed in those spaces while the sensor nodes were placed in a subcutaneous pocket. Following surgery, the pigs were kept in a holding pen in a vivarium while the computer and radio receiver were set up outside the pen to collect the data. At this point, the pigs were fully conscious and ambulatory. After 24 days, the pigs were sacrificed and the devices were explanted. A brief necropsy was performed to look for tissue inflammation or any immune response to the silicone packaging. The devices were later inspected for any damage, leaking, or any other failure points if necessary.3 Results & discussionTesting of the fully assembled lead and sensor node showed a rapid and linear response (1.34 psi/V) of the sensor. When the device was disassembled and reassembled following the initial tests, the offset was observe