Bluetooth technology is a communication protocol for personal wireless networks. It originated from an advanced short-range wireless communication technology jointly launched by Ericsson, IBM, Intel, Nokia, Toshiba and other companies in 1998.
In February 1998, led by Ericsson, a special interest group (SpecialInterest Group) was established with Toshiba, IBM, Intel and Nokia to jointly launch Bluetooth radio access technology, which is to establish and use a universal, advanced wireless interface on a global scale. technical standard. Thousands of companies have so far participated in supporting and developing Bluetooth technology and related products.
The ultimate goal of Bluetooth technology is to establish a global unified wireless connection standard, so that various mobile, portable devices and fixed terminals produced by different manufacturers can be automatically connected by radio within a short distance to achieve interoperability and data sharing.
The Bluetooth system generally consists of four functional units: an antenna unit, a link control (firmware) unit, a link management (software) unit, and a Bluetooth software (protocol stack) unit, as shown in FIG.
With its unique and practical charm, Bluetooth technology has attracted a lot of attention since its inception. It is embedded in various portable devices through a 9mm*9mm microchip and Bluetooth wireless transceiver, and the transmission distance is 10 meters, replacing all digital devices. Wired interface on. For example, the connection between the computer, the host computer, the keyboard, the printer and the display via Bluetooth technology can eliminate the confusing connection line; the mobile phone application Bluetooth technology can separate the mobile phone and the earphone, and facilitate driving and business activities. It can be seen that Bluetooth technology can continue to expand the scope of use with the needs of people, and has increasingly entered various industries, and is also gradually introduced in medical equipment.
With the continuous development of modern society, modern medical undertakings have also flourished. The emergence of hospital ward monitoring systems and medical consultation systems has made outstanding contributions to the development of modern medical services. However, the biggest drawback is that the cable on the patient not only causes great inconvenience to the patient's actions, but also has to interrupt the monitoring of the patient's condition or require human monitoring when the patient needs a large area of ​​activity.
First, the application of Bluetooth technology in modern medical electronic equipment
The main mode of Bluetooth system application in the medical field is shown in Figure 2:
1. Most of the applications that Bluetooth originally considered were used to replace wired connections. Medical equipment is basically an independent system in the hospital. Therefore, all kinds of equipments are equipped with their own peripheral systems such as computer systems and printers. The data lines are connected independently. Therefore, the status of the machine is read and the equipment is reconfigured. Sensor data, patient data, patient monitoring, safety access data, asset tracking, etc. are all independent systems for safety reasons. The most common phenomena, such as operating room, radiology department, can be seen everywhere, cable connections, staggered On the ground, once the instrument malfunctions, it takes a lot of effort for the doctor to check whether each interface is connected along the wire. It is very troublesome to organize the line, which wastes a lot of time, and the language is very valuable for saving the patient. In the case of each device with Bluetooth technology connection, the trouble of the medical device user is solved.
2. Some medical instruments, such as electroencephalograms such as EEG and electrocardiogram, receive electrical signals from the patient's body surface and transmit the bioelectrical signals to the medical device through the cable for analysis. In the meantime, because of the connection of the cable, the position and movement of the patient are limited, and the physical examination can only be performed in the lying position, so that the bioelectrical signal of the patient moving in a certain range in other postures and even in the state of motion cannot be known.
3. Some medical restricted areas, such as laminar flow wards, operating rooms, radiography rooms, radiotherapy rooms, rescue rooms, etc., are not suitable for all medical personnel to enter and exit, must have a strict isolation system, Bluetooth can play in these places Very useful, the doctor can make some inspections and treatments wireless remote control, reducing the probability of direct staff access, while not hindering the doctor's treatment and consultation work.
Second, the realization conditions of Bluetooth in electronic medical equipment
1. In the multi-machine communication, the host must be guaranteed and selected.
The slave communicates reliably, and the communication interface must have strong recognition capability. It is more susceptible to interference for Bluetooth multi-machine communication. Therefore, in addition to requiring as little external interference as possible, a relatively reliable communication protocol is required. (Chen Dejun Zuo Wei Jiang Desheng, Bluetooth technology application, Chinese core journal "Microcomputer Information" (Embedded and SOC) 2007, Vol. 23, No. 4-2, 262-264) 2. Composition of the Bluetooth protocol: Bluetooth protocol as The open short-range high-speed communication standard mainly includes the following four aspects: Bluetooth core protocol (BB, LMP, L2CAP, SDP), cable replacement protocol (RFCOMM), telephone control protocol (TSC Binary, AT command set), and Optional protocols (PPP, TCP/IP, DUP/IP, OBEX, WAP, ...). Depending on the application, the Bluetooth protocol can be flexibly configured and encouraged to utilize as many high-level protocols as possible to ensure convergence of existing network technologies with Bluetooth technology. Therefore, in addition to the Bluetooth core protocol is required, the other three aspects of the agreement depends on the specific needs of the application.
3. Requirements and implementation of physiological electrical signal transmission: Physiological electrical signals are electrical signals that are transformed into specific characterizations produced by organisms, tissues, organs, cells, etc. in life activities, reflecting specific life activity details. . Here mainly refers to Bluetooth data transmission for one-dimensional physiological telecommunications, such as: heart sound, electrocardiogram, brain electricity, myoelectricity, stomach electricity, and physiological parameters such as blood pressure, pulse, and breathing that are converted into electrical signals.
According to the frequency of the signal can be divided into three categories: (1) low-frequency signal, that is, the highest frequency is 250Hz, represented by ECG; (2) medium-high frequency signal, mainly heart sound; (3) broadband high-frequency signal, refers to myoelectric . Since there are 7 kinds of ACL data packets in Bluetooth, DMI, DM3, and DM5 packets are suitable for physiological signals with two kinds of check mechanisms. In 8-bit or 12-bit sampling systems, low-frequency signals such as ECG should be used as DM1 data. For grouping, heart sound signals should be grouped with DM3 data, and EMG signals should be grouped with DM5 data.
Third, the realization goal of Bluetooth in medical electronic equipment
1. Suppress radio electromagnetic interference: Bluetooth works in the global 2.4GHz ISM (ie, industrial, scientific, medical) frequency band. Bluetooth data rate is 1Mb/s. The frequency hopping technology divides the frequency band into several hopping channels (Hop channel). In one connection, the radio transceiver continuously continually moves from one channel to a certain code sequence (pseudo-random code). In another communication channel, the transmitting and receiving parties in the Bluetooth system communicate according to this rule, and other radio devices cannot work in the same manner. So the radio has been largely suppressed.
2. Establish "Personal areanet": Bluetooth uses spread spectrum technology to minimize the effects of noise throughout the Bluetooth band. Compared with other systems working in the same frequency band, Bluetooth FM is faster, Bluetooth devices are lower power consumption than other wireless communication devices, Bluetooth technology radio transceivers can link up to 10 meters, using high gain antennas Extend the effective communication range to 100 meters. Not limited to a straight line range, even devices can be linked to each other in the same room, and can link multiple devices, up to 7 activities, up to 200 online devices, so that the devices around the user can be linked Get up and form a "personal micro network."
3. Do not affect the bioelectrical signal: Bluetooth technology has the advantages of stable transmission signal, is not susceptible to interference and is not obstructed by objects. Under normal circumstances, it can effectively replace the medical sensor and analysis of patients in the traditional ward monitoring system through Bluetooth technology. Cables between analytical devices such as instruments, PDAs, and computers.
The wireless real-time monitoring of human life parameters is the common aspiration of the majority of doctors and patients, but it is inevitable due to the realization of traditional electronic technology. Bluetooth can not only replace the data cable around the PC, but also meet the wireless needs of patients in the ward. Through the Bluetooth gateway of the ward, the seamless connection between the Bluetooth monitoring network and the wired LAN can be realized, thereby combining the advantages of many different networks to bring a simple and comfortable environment for patients.
Fourth, the use of Bluetooth security issues
The use of any medical device must first ensure the absolute safety of the person before it can be put into clinical use before it can be accepted by both doctors and patients. Security includes information security and ecological security.
Information security
Experiments have shown that the use of microwave ovens will slow down the data transmission speed by 300k/s. In addition, spread spectrum equipment, frequency hopping equipment, wireless LAN, etc. will slow down the data transmission speed. However, the international SIG has experimented in various environments. Low-power Bluetooth products have little interference with other similar products. On the contrary, the interference of other products on Bluetooth can be solved by software or hardware. Therefore, information security issues are more emphasized in the software protocol stack, and are mainly solved by software engineers.
2. Ecological security
The ecological security problem refers to whether the Bluetooth device is dangerous when it is close to the human body, and whether there is ionizing radiation or the like. This is a problem that both doctors and patients are very sensitive. A team composed of experts from the World Health Organization and the IEEE said that the radiation of Bluetooth products was not found to have an impact on the human body during the test. The problem of Bluetooth is mainly due to the frequency range of Bluetooth and microwave oven. Whether it will bring bad consequences. Although it is still inconclusive, some organizations believe that the Bluetooth output power is very small, only 1mW, which is the million parts of microwave oven power. One is only a fraction of the radiation of a mobile phone, and only a small fraction of these outputs are absorbed by the object, and there is substantially no local temperature increase. Since the ideal connection range of Bluetooth is 5 cm to 5 m, the distance can be extended to 100 m by increasing the transmission level, so it is safer to further reduce the Bluetooth output power and shorten the connection range as needed. It is.
In the long run, the opportunities for Bluetooth to replace existing cable systems will continue to increase, and the speed of development will be faster in the short term. Although the speed of increasing the production capacity through wireless connection is slow, the long-term potential is large and there is a good development prospect.
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