| Sleep accounts for one third of human life and is an indispensable physiological need.The quality of sleep has become an important indicator for assessing physical health.At present,traditional sleep monitoring sensor devices have been unable to meet people’s needs for comfortable and convenient sleep monitoring.There have been many research advances in new sleep monitoring sensors,but most of these sensors focus on the changes in breathing rate and the movements of the limbs or the trunk during sleep,while ignoring the movements of the head,a key part of the body.In this paper,a high-resolution,pressure-sensitive,non-invasive,comfortable,and breathable smart pillow is developed based on flexible and breathable triboelectric nanogenerator(FB-TENG)sensor arrays,which can monitor head movement in real time during sleep.The main research contents of the paper are as follows:(1)A FB-TENG was assembled with porous polydimethylsiloxane(PDMS)sponge fabricated by the sacrificial template method.Morphological characterization and mechanical property tests were carried out on the citric acid monohydrate(CAM)particles used by the sacrificial template method and the fabricated porous PDMS.By optimizing the size of citric acid monohydrate(CAM)particles,it was found that the electrical output was relatively optimal when 74±6μm CAM particles were used.In addition,by adjusting the mass percentage of fluorinated ethylene propylene(FEP)powder added,it was found that the electrical output of the FB-TENG reached a maximum when 10 wt%FEP powder was doped.(2)A series of basic electrical output performance tests were carried out on the optimized FB-TENG(made from 74±6μm CAM particles and 10 wt%FEP powder).For example,its open circuit voltage,short circuit current and transferred charge under different frequencies,different external resistances and capacitances,different applied external forces and different relative humidity conditions were tested.In addition,the durability and pressure sensitivity of the FB-TENG were also tested.The results show that FB-TENG has excellent performance stability,and it has high sensitivity in the pressure range of<15 k Pa.(3)A smart pillow was fabricated by combining FB-TENG arrays and ordinary pillows.Combined with flexible printed circuit board(FPC)technology,an 8×8 FB-TENG sensing array was fabricated to realize simple touch sensing and motion trajectory monitoring.Then,a 5×12 FB-TENG sensing array was spread on an ordinary pillow to fabricate a smart pillow,which realized the monitoring of head posture and movement trajectory.In addition,a danger warning function was designed,which would send out an alarm when the baby,the elderly or the unconscious patients were in danger of falling out of bed.The array unit size of this smart pillow was only 2×2 cm~2,which greatly improves the resolution of TENG-based sleep monitoring sensors.And the average pressure of the head on the smart pillow(12.5 k Pa)was located in the low pressure region(<15 k Pa)of the FB-TENG.In this paper,a high-resolution,pressure-sensitive,non-invasive,comfortable and breathable smart pillow is designed based on the FB-TENG sensing array,which realizes the monitoring of head movement trajectory and posture change during sleep.Smart pillows facilitate our analysis of sleep behavior and provide a novel and feasible solution for sleep monitoring. |
