Tuesday, 25 February 2014 05:57

Using Zigbee to Integrate Medical Devices

Written by

Proceedings of the 29th Annual International

Conference of the IEEE EMBS

Cité Internationale, Lyon, France

August 23-26, 2007.

Using Zigbee to Integrate Medical Devices

Paul Frehill, Desmond Chambers, Cosmin Rotariu

Abstract— Wirelessly enabling Medical Devices such as Vital Signs Monitors, Ventilators and Infusion Pumps allows central data collection. This paper discusses how data from these types of devices can be integrated into hospital systems using wireless sensor networking technology. By integrating devices you are protecting investment and opening up the possibility of networking with similar devices.

In this context we present how Zigbee meets our requirements for bandwidth, power, security and mobility. We have examined the data throughputs for various medical devices, the requirement of data frequency, security of patient data and the logistics of moving patients while connected to devices.

The paper describes a new tested architecture that allows this data to be seamlessly integrated into a User Interface or Healthcare Information System (HIS). The design supports the dynamic addition of new medical devices to the system that were previously unsupported by the system. To achieve this, the hardware design is kept generic and the software interface for different types of medical devices is well defined. These devices can also share the wireless resources with other types of sensors being developed in conjunction on this project such as wireless ECG (Electrocardiogram) and Pulse-Oximetry sensors.

Keywords—Biomedical Telemetry, Medical Devices, Bioinformatics, Wireless Sensor Networks, Healthcare Information Systems.


MANY devices that exist today by the bedside in the hospital ward, intensive care unit or other clinical setting have data output features over serial ports and other types of interfaces such as USB. These devices are usually considered a significant investment and are usually purchased in an ad hoc fashion as required when finance becomes available. The consequence of this is that devices are often from different manufacturers that don’t support any standard protocol. This can make integrating these devices into a single network difficult.

In the hospital ward Vital Signs monitors, Ventilators and Infusion Pumps of many different brands are usually portable and wheeled from patient to patient as required. By networking these devices the hospital gains all the advantages associated with storing patient data centrally in electronic records. By making the device part of a wireless sensor network such as a Zigbee [1] network there are several more advantages including, cable replacement, mobility and location management. Once these devices are networked they can also use the infrastructure of other deployments of similar wireless sensor networks in the surrounding environment.

To achieve this type of solution each device must be fitted with a piece of hardware that will act as a serial to wireless bridge, a Medical Device Interface (MDI). This MDI will allow the device to receive and transmit data within the wireless sensor network. This inexpensive hardware will be generic to fit a wide range of medical devices. Similarly the firmware can be kept generic and any specific device communication protocols can be implemented on a server on the network backend.

The work described in this paper is part of a larger project,the goal of which is to provide a complete patient monitoring system. Other features of the overall system will be to provide ECG (Electrocardiogram) and Pulse-Oximetry data in a novel way over a wireless sensor network using expertise gained on prior projects [2].


The concept of using wireless sensor networks for Medical Care and wireless patient monitoring has been explored by others but integrating data from other devices is generally not discussed. There is ongoing related work in patient monitoring using wireless sensors such as the “CodeBlue”project at Harvard [3]. Others have also proven successful with wireless sensor networks designs for medical sensors [4] and in the management of sensor data [5]. It has been identified that it is desirable to wirelessly enable existing medical devices that provide vital signs data using technologies such as Zigbee [6], [7]. The research described in this paper aspires to meet these requirements. The use of wireless sensor networks within the hospital has been extensively examined. Moreover, other wireless technologies within the same frequency band, such as IEEE 802.11 [8], have existed within the hospital for some time [9].


A. Wireless Technologies

Established standards for wireless applications, such as Bluetooth [10] and IEEE 802.11, allow high transmission rates, but at the expense of power consumption, application complexity, and cost. Zigbee offers low cost, low power devices that can communicate with each other and the outside world. ZigBee's self-forming and self-healing mesh-network architecture lets data and control messages pass from one node to another by multiple paths. This is particularly useful in a hospital environment where interference from walls, people and general obstacles is a major issue. Zigbee is based upon the IEEE standard 802.15.4 [11] for radio hardware and software specification.

B. Mobility

Zigbee enabled devices support a sleep mode. An off-line node can connect to a network in about 30 ms. Waking up a sleeping node takes about 15 ms, as does accessing a channel and transmitting data. If the requirement is to collect data once a minute the device can be placed in a power saving mode saving significant amounts of energy and increasing the battery life. In sleep mode a zigbee chip can assume as little as 1.0uA [12]. This is particularly important in a medical setting where patients are often on the move while still attached to medical devices.

C. Co-existence

Both Zigbee and IEEE802.11 operate in the license-free industrial scientific medical (ISM) 2.4GHz frequency band.IEEE802.11 is already in widespread use within hospitals which would encourage the adoption of Zigbee solutions in the same environment. However care has to be taken to avoid interference between these 2 neighbouring technologies as described in the paper entitled “Coexistance of IEEE802.15.4 with other systems in the 2.4GHz-ISM-band” [13]. By selecting an appropriate channel, after performing a simple site survey, these problems can be easily avoided.

D. Device Parameters

Typical readings available on a ventilator are Inspiratory Tidal Volume, Expiratory Tidal Volume, O2 concentration,Respiratory Rate, Peak Pressure, Expired Minute Volume and Mean Airway Pressure. The settings on the ventilator are also of interest to medical staff. The most typical settings we’ve chosen are Inspiratory Tidal Volume, Minute Volume, O2 Concentration, I:E Ratio, Breath Duration and Inspiratory Flow.

Similarly we have chosen some common parameters for Vital Signs Monitors. These are Respiratory Rate, Non Invasive Blood Pressure, SPO2 and Temperature. The third device we selected parameters for is the Unfusion Pump. The common parameters we are most interested in here are Volume, Time, Ramp and Occlusion Pressure. Further parameters can be easily added to the system in the future.

E. Bandwidth

For development purposes we analysed a Maquet Servo-I [14] which supports all the ventilator parameters described above. This ventilator works in a command response manner.When initial configuration has taken place 2 commands which are 7 bytes long each will produce 2 responses of 67 bytes each. Therefore even in a multi hop mesh network it is anticipated we would be able to support several of these devices plus other types of devices on the same 802.15.4 channel.




29IEEE EMBS国际程序会议

城市  法国里昂













使用无线传感器网络的医疗服务和无线病人监测的观念一直被别人探索着,但是将数据从其他装置进行整合通常不被讨论。目前正在进行的有关病人监护仪的工作,例如使用无线传感器如“ CodeBlue ”项目在哈佛大学[ 3 ] 开展。其他人同样也成功地使用无线传感器网络设计的医疗传感器[ 4 ]和管理中的传感器数据[ 5 ] 。它已被确定,这是可取的,通过无线方式使现有的医疗设备,提供生命体征数据,使用的技术,例如ZigBee[ 6 ] [ 7 ] 。本篇论文所描述的研究力图满足这些要求。使用无线传感器网络在医院进行了广泛的审查。此外,其他无线技术在相同频段,如IEEE 802.11标准[ 8 ] ,已经被在医院一段使用时间[ 9 ]


A 无线技术

无线应用的既定标准,如蓝牙[ 10 ]IEEE 802.11,允许高速传输速率,但是代价是牺牲能耗,应用复杂性和成本。ZigBee提供低成本,低功率的设备,可以互相交流和外面的世界。ZigBee的自我形成和自我调整的网络架构让数据和控制信息从一个节点传输到另一个多个路径。这是在特别有用的在医院的墙壁干扰,和一般人的阻碍下,是一个重要问题。ZigBee是基于IEEE标准802.15.4 [ 11 ]无线电的硬件和软件规范。

B 调动

实用ZigBee功能的设备,支持睡眠模式。离线节点可以连接到一个网络中的大约30毫秒。唤醒一个沉睡的节点约需15毫秒,因为没有进入的渠道和传输数据。如果要求是收集数据,那么该设备可以放置在省电模式节省大量的能源和提高电池寿命。在睡眠模式的ZigBee芯片可以承担少1.0uA [ 12 ] 。这一点尤其重要,在医疗环境中,病人往往是在轮椅上移动的时候仍然被连接到医疗设备。

C 角共存

ZigBeeIEEE802.11工作在免许可证的工业科学医疗协会( ISM )的2.4GHz频率频段.IEEE802.11已经广泛使用在医院,医院将鼓励通过ZigBee解决方案促使在同一个环境中使用。但是必须注意,以避免干扰这些本论文所描述的两个相邻的技术文件,题为“共存的IEEE802.15.4与其他系统工作在2.4GHz频带” [ 13 ] 。通过选择一个适当的渠道,在一个简单的现场调查表现,这些问题可以很容易地避免。

D 器件参数

可以在呼吸机进行典型的读数如吸气潮气量,呼气潮气量,氧气浓度,呼吸速率,峰值压力,过期每分通气量和平均气道压。医务人员对于仪器上的通风设备也感兴趣。我们已选择的最典型的设置是吸气潮气量,每分通气量,氧气浓度,I E比值,呼吸时间和吸气流量。同样,我们选择了一些常见的参数,生命体征监测器。这些都是呼吸速率,无创血压,血氧饱和度和温度。第三个器件参数,我们选择的是传感频率泵。我们共同最感兴趣的参数是这里的工作量,时间,接线端扭和闭塞压力。进一步参数可以很容易地在后来添加到系统中。

E 带宽

我们分析了支持所有上述呼吸参数的Maquet Servo-I,发现已达到完善的目的。这种呼吸器工作在命令作反应方式。当初始配置发生改变,7字节长的两个命令,每个生产2答复每个67字节。因此,即使是在一个多跳网状网,我们预期将能够支持一些这类设备加上其他类型的设备工作在同一802.15.4频段。


F. Scalability

The ventilator, having the most parameters of the devicesstudied, requires the most bandwidth. Experiments carried outon a CSI Vital Signs Monitor [15] show that 44 bytes of data will produce all the information we are interested in. A BraunInfusion Pump [16] exports 24 bytes of data to produce the 4 parameters we need. For any of the medical devices we are concerned with, the readings are typically only required once aminute in a hospital environment. All these devices have their own alarm mechanisms built in; we are purely providing a means of exporting the data automatically. Theoretically a single Zigbee network could have above and beyond 600 Ventilators as each device only requires less than 1KB of bandwidth per minute. The frequency at which we capture the data is decided upon by the clinical staff themselves. A 1 minute interval is a typical value, however even if they were to require the data every few seconds it is clear the network could still support a large number of devices.


A. High-Level Architecture

The overall System Architecture consists of a Wireless Personal Area Network (WPAN) and a Local Area Network. The WPAN implemented as a Zigbee network communicates with the LAN via a gateway. This gateway also serves as the WPAN coordinator which is responsible for forming the network. Each medical device has a Zigbee node attached(MDI) which enables data to be transmitted wirelessly to the Gateway and then onto a Server existing on the LAN. See

Fig. 1 below for a graphical representation of this. When an MDI is powered on it automatically joins the network and makes itself known to the Server. A user can then associate

this device with a patient using a GUI client. Once an association has been completed the MDI will be notified to begin transmitting data. Data received by the server will be stored in the Electronic Health Record (EHR) for that patient and displayed on any GUI Client that is subscribed.


Figure 1. High-Level Architecture

B. Medical Device Interface

The diagram in Fig. 2 below shows the key components of the MDI. The hardware comprises of a Zigbee module, a microcontroller and an RS 232 Interface. The microcontroller is responsible for interfacing with both the RS232 Interface and the Zigbee module.


Figure 2. MDI Block Diagram

When the MDI is powered on, the Zigbee stack will automatically join a Zigbee network within range. Next the MDI will announce an ID which is also visible on the external surface of the device. This is done using a protocol we designed for this project. The protocol supports these types of status messages in addition to supporting the actual real data we are interested in. At this point it is possible to make an association with the MDI. To achieve this, the administrator

selects the ID from an automatically generated list on screen, a patient demographic and a type of medical device which is supported in the system. This process results in the server sending the correct RS232 settings to the MDI for the medical device that it is connected to. Now that the system can communicate directly with the medical device the server will send any necessary commands to initiate a data stream from the device.

C. Server Functionality

The server is responsible for decoding specific medical device data. This functionality is implemented in a DLL (Dynamic Link Library) that is run on the server. There is one

DLL for each type of medical device the system supports which allows for future medical devices to be supported without upgrading the server software. Any future device can easily be supported within the DLL framework by simply inheriting from the appropriate class for that particular type of device. These DLLs are loaded at run-time and have a standard interface that each designer must adhere to in order to interoperate with the system. A designer must also complete an XML file from a template to indicate which features the new medical device supports. The DLL only handles device specific information; the main server application decodes this information from our project protocol.


Figure 3. New Data Request

When the DLL is loaded by the server application it will receive a value to represent how frequently the server wants GUI data. This value is used to create the interval timer represented in the above UML diagram. When this timer expires the DLL will check the current state it has for the ventilator. Fig. 3 above shows an activity diagram representing a sequence of events surrounding this timer expiration in a DLL for a ventilator. When the timer expires the DLL retrieves the command in the form of a byte array of ASCII characters. Next the DLL raises an event containing the byte array. The server application accepts this event through its event handler, encodes it in our protocol and sends it to the medical device.

Figure 4. Handling New Data

When the medical device returns a response to the server application this data is passed to the DLL as shown in Fig. 4 above. If the DLL does not receive any data within a specified timeout period the DLL will re-initiate communication with the medical device. Data that is received by the DLL is checked to see if it is consistent with the format expected and that the checksum is valid if applicable. Once the data is proven to be valid, a generic data structure that is shared

between the server application and clients is populated. Finally the DLL will raise another event, this time to indicate that GUI data is available. The server then multicasts the new data to any client that is subscribed to that address. The Server could be extended to integrate with existing

hospital systems using HL7 [17] or another uniform interface that is designed specifically for wireless sensor networks could be used such as that developed by DERI [18].


The architecture described here has been implemented and tested successfully in a laboratory environment. For this purpose we connected the MDI to a PC simulator designed to act as a Maquet Servo-i ventilator. The Maquet ventilator can return breath readings and settings. To capture these, the SDADB and SDADS Maquet commands are sent to specify which breath readings and settings we wish to retrieve. Then by sending the RADAB and RADAS commands periodically we can capture up to date information from the ventilator.Fig. 6 shows the simulator handling these commands at runtime.


Figure 6. Ventilator Simulator

As described in the Architecture the Server DLL maintains a state for each end device so it knows what information to expect in return. In our experiments we successfully retrieved ventilator data at 5 second intervals. We have designed a GUI client which we successfully subscribed to receive this ventilator data. We are collaborating with a local hospital that use the Maquet ventilator and their requirement is data collection at 1 minute intervals. These results are very positive prior to usability tests in the hospital with the actual ventilator. We also performed a limited amount of range testing in the laboratory. We achieved a range of 20m within the confines of the laboratory which would equate to the maximum distance between an end device and a router in the hospital. In addition we carried out some mobility testing by moving the MDI during operation which did not result in any packet loss. Initial results are positive but further extensive testing is needed which will be performed in the hospital environment.


In this paper we have shown that a Wireless Sensor Network is a suitable means for capturing data from a medical device. We have discussed how Zigbee meets our requirements in terms of data throughput, power and mobility. Moreover, using this technology we can develop a low cost, scalable solution for a wide range of medical devices. In addition we have an infrastructure that allows us to easily support new devices within the system as needed. This architecture facilitates moving the device data to third party systems and to our own User Interface. We hope that our field trials will result in positive feedback from the clinical staff.


通风设备,拥有最多的装置参数研究,需要最多带宽。实验进行在CSI的生命体征监测[ 15 ]表明,44字节数据将产生的所有我们感兴趣的信息。A Braun输液泵[16]出口24字节的数据,以产生4我们需要的参数。对任何我们正关心的医疗设备,典型的数据通常只需要一分钟一次在医院环境。所有这些设备都自己建造的报警机制;我们完全提供了一个输出数据自动的方法。理论上1个单一的ZigBee网络可以有超越600个通风机当每个设备只需要每分钟不到1KB的带宽时。我们捕捉的频率数据被临床工作人员本身所决定。A1分钟的间隔是一个典型的价值,然而即使他们被需要的数据每隔几秒钟,很明显网络





1 高级架构




2 MDI方框图





3 新的数据请求


4 处理新数据






此架构所述的已被实施和测试非常成功在实验室环境中。为此目的我们连接MDIPC模拟器设计作为Maquet伺服系统呼吸器。该Maquet呼吸器可以返回呼吸读数和设置。为了获取这些,该SDADBSDADS Maquet指令发送到指定的我们希望检索的呼吸读数和设置。然后通过定时地发送RADABRADAS命令

我们可以捕捉最新的信息从呼吸器。图 6显示在运行时间模拟器处理这些命令


6 呼吸机模拟器








Saturday, 30 March 2013 08:32


Written by


Thursday, 07 March 2013 10:57


Written by



热键(hot key)。菜单命令和对话框选项中带有下划线的字母或数字。通过按下Alt键和下划线的字母或数字,可以机或命令和选项。

超文本标示语言(Hypertext Markup Language)SGML语言的子集。定义了一组标示符控制页面内容的显示方式。

输入方法编辑器(Input Method Editor-IME)。通过按下键盘的多个键完成输入本地化文字的应用工具。对于汉字,常用的有微软拼音输入法,标准输入法,五笔字形输入法等。


国际化测试(international testing)。软件国际化的支持和可本地化能力的测试方法。


启动会议(kick-off meeting)。新的本地化项目正式开始前的会议,一般由原软件开发商和本地化服务商中的项目组主要代表人员参加。主要讨论项目计划,各方责任,提交结果,联系方式等与项目紧密相关的内容。

分层图像(layered graphic)。为了便于翻译,可以翻译的文字单独存放在文字层的图像。


语言测试(linguistic testing)。对本地化的产品执行与语言有关的内容的测试活动。

本地化行业标准组织(Localization Industry Standard Association-LISA)1990年在瑞士成立,成为本地化和国际化行业的首要协会,目前已经加入的会员超过400多家。LISA的目标是促进本地化和国际化行业的发展,提供机制和服务,使公司间能够交换和共享与本地化、国际化和相关主体相关的流程、工具、技术和商务模型信息。


本地化工具包(localization kit)。由软件开发商提供的包好文件、工具和指导文档的系列文件集。本地化项目开始前,软件开发商提供给本地化服务商。

本地化测试(localization testing)。对本地化的软件进行语言和用户界面测试,以保证软件本地化质量的活动。

本地化服务商(localization vendor)。提供本地化服务的机构,包含软件翻译、软件工程、测试和项目管理等活动。

机器翻译(machine translation-MT)。利用术语表、语法和句法等技术,自动实现从一种人类语言到另一种语言的翻译的方法和技术。

标识语言(markup language)。与文字结合的标识和标签集合,应用程序(例如HTML网页浏览器)将处理这些标识并以正确的形式显示出来。

多字节字符集(multi-byte character set)。每个字符用单个字节或两个字节表示的字符集。

多语言服务商(multi-language vendor-MLV)。提供多种语言软件本地化能力的服务商。大多数多语言服务商主要集中在多语言项目的项目管理上,它们在全球范围内由多个分公司和合作伙伴。

国家语言支持(national language support-NLS)。允许用户设置区域等软件功能。识别用户使用的语言、日期和时间格式等信息。也包括支持键盘布局和特定语言的字体。


便携式文档格式(Portable Document Format-PDF)。由Adobe公司开发的基于PostScript标准的文件格式。PDF文件可以由其他软件创建,主要用于电子文档的发布。

伪翻译(pseudo translation)。将软件中的可以翻译的字符串用长的本地化的字符代替的自动或手工处理的过程,主要用于发现编译和执行本地化文件时潜在的问题。

质量保证(quality assurance-QA)。保证最终产品质量的步骤和流程。

报价单(Request for quotation-RFQ)。软件开发商发送给本地化服务商的包含项目内容和报价的报价单。

投入回报率(Return of Investment-ROI)。判别项目投入费用和受益回报的指标。


资源动态链接库(Resource-only .dll )。包含可以本地化的资源,例如,菜单、对话框、图标、屏幕提示字符的动态链接库。

屏幕捕捉(screen capture, screenshot)。使用图像截取软件截获菜单和对话框等软件界面的过程。

Thursday, 07 March 2013 10:53


Written by


































Thursday, 07 March 2013 10:50


Written by





  软件本地化翻译的需求最初来源于软件的本地化需要,所以自然就会借鉴很多软件工程的项目管理方式和经验,再加上软件本地化在美国和欧洲做的比较早,他们的语言之间具有近似性,这两个特点促成制定了很多软件本地化的流程规范和翻译规范。具体到翻译层面,项目中会有很多 style guide 内容,新手适应这些规范需要一定的时间,而要从事这个领域的翻译,就必须要了解这些规范。很多项目字数可能不多,而需要阅读的 style guide 内容可能会有上百页。当然对于老手,可以凭借经验则其要点,而对于新手,需要一个适应过程。

另一方面,规矩多多,对于翻译这项创意性的工作也是一种束缚,有的时候甚至会扼杀创造性,妨碍翻译内容的准确表达,让翻译工作和翻译内容都索然无味。这也就需要大家有“带着脚铐跳舞”的心理准备,遵守规范的同时要掌握一个度 —— 遵守规范和翻译标准是第一位,在这个基础上再尽量寻求灵活性。



  这里要强调的就是,本地化翻译的一个通病在于翻译时缺少上下文连贯性,看似简单的翻译,如果不注意前后的衔接,也可能让读者不知所云。这可能是拜 Trados 断句之所赐,但也体现了翻译人员不注重上下文的问题。任何简单的工作都有出彩之处,扫地也可以扫出花来。翻译更是如此,没有最好,只有更好。当然翻译公司大多并不会注重你的“更好”,你只需合乎规范就可以了,正如版主 thinkcell 曾经的经典评论:“本地化翻译是不求有功,但求无过”,这是题外话了,暂且不谈。


  一个合格的软件本地化翻译,需要掌握一定的 IT 知识;需要熟悉各种规范,能快速适应新的规范;翻译过程中能够注重上下文的连贯性,需要有点钻牛角尖的专业精神;当然,英文和中文表达也要足够好。