Building And Test Of Wearable Wireless Network Based On Knitted Flexible Sensor

Wearable wireless sensor network refers to a wireless network which monitors automaticallybiological data of human body (heart rate, blood pressure, breath and body temperature), externalconditions (temperature, location, air composition moisture) and sporting information (energyconsumption, pace, trail and speed) in a continuous, everlasting and dynamic manner.Smart clothing can not only detect the information about outside environment andanalyze them, but also summarize the results of these analyses and finally guide wearer to takeaction accordingly.It can improve wearing comfort and flexibility of movement when smart clothing combinewith wearable wireless sensor network, which helps to promoting research of wearable wirelesssensor network and development in customer-friendly and more practical direction.This paper proposes a wearable wireless sensor network. During the process of building thenetwork, it mainly accomplishes the following jobs:(1) Based on ZigBee, the wireless networkand transmit system were built, which contributed to the communication between the end deviceand the coordinate device. This ZigBee wireless network was made by the second generationsystem on a chip—CC2530system chip and Q2530RF chip, manufactured by TI Company, whichis in the2.4GHz frequency band and supports IEEE802.15.4/ZigBee agreements. Two enddevices on smart clothing collecting heartbeat and respiration signals, one coordinate deviceoutside the clothing were designed, and these three devices formed a star topological structure.(2)The circuit was designed to allow the combination of the end device and the knitted flexiblesensor, then ZigBee network was joined, this smart clothing with the knitted flexible sensorstransmitted the physiological signals of the human body to the coordinate device by the way ofasynchronous communication.(3) The serial port communication between the coordinate device and upper computer was achieved by the MSComm control of Visual Basic6.0, the host computercan receive the physiological signals collected by knitted flexible sensors. Then the relevanrfunctions were called to show the received signals presented in the way of sensor voltagechanging curve, meanwhile the data were saved in the corresponding file.(4) The tensileexperiments were implemented to the knitted flexible sensors with22courses×200wales toexplore the mechanicals–electricity performance of the sensors. Then the knitted flexible sensorswith22courses×240wales were made the same experiments to check the previous conclusionssummarized by the former experiments. In the end, the conclusions come to: among the presentthree fixed resistances--7.5Ω，15Ω，30Ω, when the fixed resistance is7.5Ω, the system has thehighest sensitivity, and the resistance of the knitted flexible sensor becomes higher as theextension is higher, or the resistance of the knitted flexible sensor becomes lower as the stretchislower.(5) The knitted flexible sensors were fabricated at fixed places of the seamless underwear,such as close to human’s heartbeat and abdomen, adopting the7.5Ω fixed resistance, to test theheartbeat and respiration of the wearer. Next, the heartbeat and respiration signals of the wearerwere tested after running fast for5minutes, rest for5minutes after running, rest for17minutesafter running to verify the sensitivity and reliability of this wearable wireless sensor network.