Detection And Recognition Method Of Posture And Pressure Information Based On Wearable Devices

The current wearable devices represented by Google Glass,Apple Watch and Smart Glove will become the"fourth platform"after TVs,computers and mobile phones.Because flexible pressure sensors have broad application prospects in wearable electronic devices,they have attracted extensive attention.So far,various flexible pressure sensors with excellent performance have been developed,but they still face many huge challenges in practical applications.For example,medical diagnosis based on wearable devices should perform accurate and rapid analysis of physiological signals,so a flexible pressure sensor with high sensitivity,low cost and large-area preparation is required.Moreover,pressure visualization can greatly promote information interactivity.In addition to sensing external stimuli,wearable devices that can convert pressure information into a human-readable form for display are of great significance.Therefore,two flexible pressure sensors based on micro-nano structure are constructed by templates in this paper.The latter is combined with electrochromic materials to form a flexible pressure visualization device,and a miniaturized wearable device system is prepared by combining wireless transmission technology to realize the detection and recognition of human posture and pressure information.The main research contents are as follows:(1)A capacitive pressure sensor based on a poly(vinylidenefluorideco-trifluoroethylene)[P(VDF-Tr FE)]dielectric film that incorporates nanopillars into both sides is designed.Unlike the previous complicated and expensive methods,large-scale and uniform nanopillars are easily and economically achieved by the pattern transfer of anodic aluminum oxide templates.The double-sided nanopillars constituting the P(VDF-Tr FE)dielectric layer enable the pressure sensor with high sensitivity(?0.35 k Pa^-1),wide working range(4 Pa to 25 k Pa),short response time(?48 ms),and excellent durability.In addition to these salient features,our sensor also exhibits superior performances under bending states,ensuring that it can be used for detecting diverse human physiological signals and body motions in real time,respectively,correspond to the low-and high-pressure range.A sensor array is finally constructed and is shown to be capable of perceiving the spatial pressure distribution of either a contact or noncontact object.(2)An integrated flexible pressure visualization device is realized,which can detect and visualize pressure stimuli in a single device.In terms of pressure sensing,supercapacitive flexible sensors based on 3D printed microstructures have high sensitivity(up to 3200 k Pa^-1),fast response speed(20 ms),wide sensing range and good cycle stability.In terms of discoloration,electrochromic devices based on tungsten trioxide(WO₃)can identify the size of the pressure and the shape and position of the object through the capacitance signal and the degree of the color change.At the same time,the pressure can be maintained and recorded for a certain period of time in the form of color.Furthermore,the introduction of a microcontroller can make the relationship between pressure and discoloration more precise,realizing the display and hiding of information under pressure control.It also demonstrated the application of repeatedly writing and erasing calligraphy on a flexible writing board.(3)In order to make the flexible pressure sensor further meet the actual application,we combine supercapacitive pressure sensors,electrochromic devices and ESP32 microcontrollers to form a miniaturized pressure information collection system.Taking smart glasses customized by light-curing 3D printer as an application display,we integrate the miniaturized system on the glass to realize the detection of posture and pressure information.It can detect human chewing and pulse information in situ and collect them through the ESP32 microcontroller.Through Wi-Fi wireless transmission,the information is wirelessly transmitted to the App on the mobile phone for real-time display.In addition to displaying the waveform changes of the data,it can also accurately measure the heart rate,showing the potential of monitoring human health.These works reflect the broad prospects of our devices in medical health monitoring,human-computer interaction and intelligent robots.