Introduction <br />Medical monitoring equipment can currently be divided into two categories. One category refers to specialized instruments used in hospitals by professional doctors or technicians to monitor patients' physiological indicators. The other category refers to remote medical monitoring systems used by ordinary people at home or outdoors, under the guidance of doctors, by patients or their families to monitor patients, and the obtained physiological indicators are transmitted to relevant doctors in a timely manner. Currently, most monitoring methods used in hospitals employ fixed medical monitors, with connecting devices linking sensor probes between the patient and the monitoring equipment for signal transmission. The complex equipment and numerous connections can cause psychological stress and anxiety for patients, potentially affecting their physical condition and leading to discrepancies between diagnostic data and the actual situation. This causes inconvenience for both patients and medical staff and may affect the accuracy of diagnosis.
To enable individuals who frequently require physiological measurements (such as chronically ill or elderly patients) to measure certain routine indicators at home while maintaining free movement, there is a growing international focus on telemedicine. This paper designs a novel network-based monitoring device and system. The aim is to utilize high-frequency, multi-channel wireless data transmission to transfer information between medical sensors and monitoring control instruments, reducing the need for wiring between the monitoring equipment and medical sensors. This allows the monitored individual more freedom of movement, obtaining more accurate measurements while relieving the burden of traveling between home and hospital. Simultaneously, in the hospital…
The establishment of a wireless monitoring network within the wards allows many tests to be completed from the patient's bedside, greatly facilitating patient visits and enhancing the hospital's modern information management and operational efficiency. Furthermore, the remote monitoring system can be expanded to enable patients far from hospitals and other medical institutions to receive necessary medical monitoring at any time, and to access remote doctor consultations and guidance when needed, such as in rural areas of my country where medical resources are scarce.
The remaining parts of this paper are as follows: Part II introduces the system architecture; Part III introduces the design method of the base station equipment used in the system; Part IV introduces the design method of the medical sensor nodes used in the system; Part V introduces the wireless communication between the base station and nodes in the system; and finally, experimental verification and conclusions are presented.
System Architecture <br />This paper proposes a remote medical monitoring system based on wireless sensor network technology. It presents a novel, scalable, multi-layered network architecture and its implementation method, consisting of a monitoring base station device and dedicated wireless sensor nodes forming a miniature monitoring network. The sensor nodes use a central controller to control the vital signs sensors to collect data. This data is then transmitted wirelessly to the monitoring base station device, which in turn transmits the data to a connected PC or other network device. Through an Internet network, the data can be transmitted to a remote medical monitoring center, where professional medical personnel can perform statistical analysis and provide necessary consultation services, thus realizing remote medical care.
Figure 1 illustrates the architecture of the remote medical monitoring system, which includes monitoring base station equipment and a series of medical sensor nodes in the medical monitoring network.
In the system designed in this paper, medical sensor nodes are used to measure various human physiological indicators, such as body temperature, blood pressure, pulse, blood glucose, and blood oxygen. The sensors can also dynamically monitor the status of certain medical devices or the treatment process. The acquired data is transmitted wirelessly to the medical monitoring base station equipment. We designed these home or ward base stations as handheld devices. The base station equipment can store and process the received sensor data and display it on the device's LCD screen. It can also choose from various methods for remote data transmission communication as needed, such as connecting to a PC via an RS2232 interface, via GSM SMS, or via a modem to access a remote Ethernet network. The information transmitted to the remote end will be statistically analyzed by professional medical personnel at the remote monitoring center or hospital management center, who will then provide timely feedback, advice, and suggestions to the patient.
The medical sensor nodes can be configured according to different needs, thus giving the system great flexibility and scalability. Furthermore, connecting the system to the Internet can create a larger community healthcare monitoring network, hospital network, or even a city-wide or national healthcare monitoring network, as shown in Figure 2.
Design of Monitoring Base Station Equipment <br />Figure 3 shows the structural block diagram of the medical monitoring base station equipment designed in this paper. The main function of this system is to collect and display the data obtained from the test, and to store and forward the data appropriately. Therefore, the monitoring base station equipment in this system is designed as a handheld device. The monitoring base station equipment can communicate with multiple sensor nodes in the system to complete data collection and display functions. During use, the monitoring base station equipment sends control commands to the sensor nodes via a wireless channel to activate the sensor nodes. After receiving the command, the sensor nodes perform corresponding data collection actions, collecting human physiological indicator data. After the collection is completed, the data is returned to the monitoring base station via wireless communication for further display, storage, and other operations. When necessary, the monitoring base station equipment can transmit data to a remote server via the network.
The medical monitoring base station equipment mainly consists of several parts, including a processor, memory, a human-machine interface module, and a communication module interface. The main processor of the medical monitoring equipment uses a low-power processor from TI's MSP430 series. This series of processors features ultra-low power consumption, high processing speed, and rich interfaces, making it very suitable for embedded devices requiring ultra-low power consumption and high speed. The human-machine interface includes a keyboard for user input commands and an LCD screen for displaying data results and operation processes.
To enhance the system's applicability and compatibility, the monitoring base station equipment is designed with multiple communication module interfaces, including an RS-232 interface, a modem interface module, a GSM short message interface module, and a radio frequency (RF) interface module. The RF interface module is used for short-range communication with wireless sensor nodes within the system, while the other communication interfaces are used for communication with the host server. For example, in situations where there is no internet access at home, users can use the modem module to connect to a telephone line to dial and transmit data to the server. Outdoors, where no other connection method is available, users can use GSM short messages to transmit data to the server. When the server at a hospital or community health center receives data from the monitoring base station equipment, it can store and analyze the data, allowing doctors to make appropriate judgments and decisions. For home-use medical monitoring equipment, users can connect the device to a home PC via the RS-232 interface, enabling more flexible management of the monitoring base station equipment's data. Family members can use the data to assess the monitored person's health status, and the data can also be transmitted to the main server for analysis and management by professional medical personnel. Figure 4 shows a hardware photograph of the monitoring base station equipment developed in this work.
The monitoring base station equipment is powered by batteries under normal operating conditions, therefore, low-power management and control are particularly important in its design. When not in use, the system enters a low-power and idle state.
To conserve system energy, it enters a sleep state.
Design of Monitoring Sensor Node <br />The main function of the medical wireless sensor node is to collect human physiological index data, or to dynamically monitor the status of certain medical devices or the treatment process, and to transmit the data to the monitoring base station equipment via radio frequency communication. As shown in Figure 5, the medical sensor node mainly consists of four parts: a processor, a data storage section, a sensor module, and an RF communication section. The processor section uses a TI MSP430 series microcontroller to meet the requirements of low power consumption and processing power. The memory section is mainly used to store temporary data collected by the sensors; after the processor transmits the data, the sensor node does not store large amounts of data. In the system designed in this paper, the medical sensor module mainly implements the following functions, including the measurement of blood oxygen, pulse, blood pressure, and blood glucose. Specifically, the blood oxygen and pulse measurement integrates the BCI blood oxygen and pulse measurement module produced by Shanghai Berry Genomics Co., Ltd.; the blood pressure measurement integrates the blood pressure measurement module produced by Taiwan TaiDoc Co., Ltd.; and the blood glucose measurement integrates the blood glucose measurement module produced by TaiDoc Co., Ltd.
Figure 6 shows photographs of the hardware circuits for these three modules. Figure 6(a) shows the blood glucose measurement node, Figure 6(b) shows the blood pressure measurement node, and Figure 6(c) shows the blood oxygen and pulse measurement nodes. In this system design, the wireless nodes provide ample interfaces for sensor expansion. If other types of physiological data, such as body temperature and electrocardiogram data, are needed, simply connect the corresponding sensors to the reserved interfaces to form new wireless sensor nodes. With the development of corresponding embedded control and processing software, these nodes can be directly added to the wireless sensor network.
Wireless Communication Design <br />Medical monitoring equipment used in hospitals has very high requirements for electromagnetic radiation. For these devices, the radiated electromagnetic waves must not interfere with the normal operation of other equipment, and they should also have a certain degree of anti-interference capability, remaining unaffected by electromagnetic waves radiated by other devices. Therefore, this aspect must be considered in the design of medical devices used in hospitals or in homes employing wireless communication.
This system utilizes the globally available and free 214GHz ISM band for radio frequency communication, employing the 802.15.4/Zigbee standard. This standard is specifically designed for short-range, high-speed data transmission and boasts strong error correction and anti-interference capabilities. Furthermore, the system controls the operating strength of the wireless signal, ensuring that under normal conditions, the signal strength is sufficient for communication without excessive waste. This conserves system energy and reduces interference to other devices during wireless communication.
The radio frequency (RF) communication device designed for this system uses an RF communication module based on the CC2420 chip. This chip, manufactured by Chipcon Corporation in the United States, is a low-power wireless transceiver chip, particularly suitable for operation in low-power, low-voltage wireless communication devices. Operating in the gratuitous 2.4 GHz ISM band, its RF transceiver complies with the IEEE 802.15.4/Zigbee standard, meeting the RF communication requirements of this system.
Experimental Verification <br />Preliminary results were obtained during the comprehensive testing of this system. The sensors collect data and transmit it wirelessly to the monitoring base station equipment. The monitoring base station equipment displays the data on an LCD screen and simultaneously transmits the data to a computer via an RS2232 interface. The computer displays the acquired data as graphs in its software. In practical applications, these graphs and data can be used to analyze the health status of the monitored individual. In outdoor environments, the measured data can be sent to a server for management and analysis via GSM SMS. Figures 7 and 8 illustrate the monitoring of the blood oxygen status of the monitored individual and the display of the data on the monitoring base station equipment and the computer.
Summary and Outlook <br />This paper introduces a scalable remote medical monitoring system based on wireless sensor networks. The system establishes a wireless sensor network in a home or hospital ward environment. Through this network, sensor nodes collect information on human physiological indicators or dynamically monitor the operation of medical instruments and the treatment process, transmitting the information to monitoring base station equipment and a server computer. The sensor network system can connect to this remote monitoring center in various ways through the monitoring base station equipment. The system has high flexibility and scalability, and can be widely applied in community telemedicine and hospital ward monitoring environments. A remote medical information network can be built through the Internet, which not only benefits patients in developed areas to access healthcare services but also benefits patients in impoverished areas to access necessary medical services. Future work will further develop the system's software and hardware to improve stability and practicality, and will also customize upper-level management software and improve the medical monitoring management platform software according to specific needs.
Edited by: He Shiping
