Flexible wide-range multidimensional force sensors inspired by bones embedded in muscle

Flexible sensors have been widely studied for use in motion monitoring,human‒machine interactions(HMIs),personalized medicine,and soft intelligent robots.However,their practical application is limited by their low output performance,narrow measuring range,and unidirectional force detection.Here,to achieve flexibility and high performance simultaneously,we developed a flexible wide-range multidimensional force sensor(FWMFS)similar to bones embedded in muscle structures.The adjustable magnetic field endows the FWMFS with multidimensional perception for detecting forces in different directions.The multilayer stacked coils significantly improved the output from theμV to the mV level while ensuring FWMFS miniaturization.The optimized FWMFS exhibited a high voltage sensitivity of 0.227 mV/N(0.5–8.4 N)and 0.047 mV/N(8.4–60 N)in response to normal forces ranging from 0.5 N to 60 N and could detect lateral forces ranging from 0.2–1.1 N and voltage sensitivities of 1.039 mV/N(0.2–0.5 N)and 0.194 mV/N(0.5–1.1 N).In terms of normal force measurements,the FWMFS can monitor finger pressure and sliding trajectories in response to finger taps,as well as measure plantar pressure for assessing human movement.The plantar pressure signals of five human movements collected by the FWMFS were analyzed using the k-nearest neighbors classification algorithm,which achieved a recognition accuracy of 92%.Additionally,an artificial intelligence biometric authentication system is being developed that classifies and recognizes user passwords.Based on the lateral force measurement ability of the FWMFS,the direction of ball movement can be distinguished,and communication systems such as Morse Code can be expanded.This research has significant potential in intelligent sensing and personalized spatial recognition.

Perpendicularly assembled oriented electrospinning nanofibers based piezoresistive pressure sensor with wide measurement range

With the rapid development of wearable electronics,flexible pressure sensors have attracted wide attention in human–computer interaction and intelligent machines.However,it is a challenge to achieve a sensor with high sensitivity,wide measurement range,and wearing comfortability.Here,we develop an oriented electrospinning thermoplastic polyurethane/polyacrylonitrile(TPU/PAN)nanofibers(OETPN)based piezoresistive pressure sensor(PONPS)in which the active layer and the electrode are assembled perpendicularly.The interdigital electrode is fabricated by spraying silver nanowires(AgNWs)on the OETPN through a mask plate.The active layer is composed of OETPN coated with MXene,encapsulated on the electrode by polyurethane(PU)film.The porous structure of nanofibers membrane broadens the measurement range of the sensor.Employing oriented nanofibers as active layer can improve the sensitivity in low pressure,because oriented nanofibers without interweaving nanofibers are more compressible than disordered nanofibers.Electrode prepared using the spraying method creates nanoscale microstructure and increases sensitivity.The perpendicular assembly has greater response between the active layer and the electrode than the parallel assembly to improve the sensitivity.The sensor exhibits high sensitivity(6.71 kPa^(−1),0.02–2 kPa)and wide measurement range(0.02–700 kPa).The sensor can detect weak signals such as radial artery.A pressure array constructed precisely represents the distribution of pressure.An intelligent throat is created by combining machine learning algorithms with the PONPS.It can detect and recognize subtle throat vibrations while speaking,achieving recognition accuracy up to 100%using support vector machine(SVM)for five words with different syllables.The fabricated sensor shows promising prospects in personal healthcare and intelligent robots.