Design And Implementation Of Flexible Force Sensing Technology Based On PDMS Grating

Flexible sensing technology plays an important role in the field of special environment monitoring and wearable devices.With the rapid development of flexible materials,various high-performance biocompatible flexible sensors have been proposed.Among these materials,polydimethylsiloxane(PDMS)is one of most popular technologies and it is highly elastic and transparent material.PDMS is made of a mixture of pre-polymer(base)and cross-linker(curing agent),that are cured at a certain temperature.In this paper,we introduce a novel force sensing device based on PDMS grating.In this paper,the PDMS grating is cast from a commercial master grating.While the relationship of elastic modulus of the PDMS grating influenced by the curing temperature and the mixture ratio are concluded by the experiments.When the PDMS grating is stretched,the diffraction light spot will shift following the grating diffraction equation.According to grating equation,the relationship between light spot shift and stretching force is established and evaluated by capturing the light spot shift using a camera.The introduction introduces the research significance of the flexible force sensor,and introduces in detail the principle,fabrication method,development status and previous research situation of the sensor.The method is inspired by the researchers,also the experience is absorbed.Besides,further improvement is proposed in this section.In the second chapter,material properties and preparation processes of PDMS flexible grating are introduced from two aspects:property and process.In addition,the use of the equipment is described in detail,and the elastic modulus of the material is calculated by tensile test.In that case,the work provides the sensing elements and theoretical support for the following analysis of the relationship between the force signal and the optical signal.Moreover,three mixing ratios of 5:1,10:1,15:1 and the curing temperature of 70?,80?and 90?were applied to prepare the PDMS gratings,respectively.In addition,the detection of grating surface is adopted to ensure the intact grating structure.The third chapter presents the principle of force sensing based on PDMS flexible diffraction grating.This method measures the tensile force through the change of diffraction spot position.In addition,the theoretical calculation,algorithm principle as well as the construction of experimental platform are also represented.Finally,a force sensing technology is designed and implemented by integrating all the schemes.The fourth chapter shows the results of the above experiments,which are mainly divided into two aspects:tensile test and force measurement experiment.The experimental results show that the linearity(R~2)of this method is greater than 0.998in the range of 0-20 N,the sensitivity is about 0.5-0.7 N/mm,and the accuracy is up to 0.05 N.In addition,the elastic modulus of PDMS decreases as the increasing ratio of the elastomer substrate,and it is positively correlated with the curing temperature.The fifth chapter is the conclusion,which summarizes and demonstrates the work content of the whole paper,points out the superiority of this adjustable flexible force sensing technology,and introduces the shortcomings and prospects of the present experiment.In this paper,a method of force measurement is presented which is based on the existing research of strain measurement.In addition,this paper adopts the soft casting process to greatly improve the accuracy,reduce the cost,simplify the demand for equipment.Also,by changing the PDMS grating manufacturing parameters to adjust the performance of force measurement.