Laser-Induced\nGraphene Strain Sensors for Body Movement Monitoring

To enable the development\nof artificial intelligence of things,\nthe improvement of the strain sensing mechanisms and optimization\nof the interconnections are needed. Direct laser writing to obtain\nlaser-induced graphene (LIG) is being studied as a promising technique\nfor producing wearable, lightweight, highly sensitive, and reliable\nstrain sensors. These devices show a higher degree of flexibility\nand stretchability when transferred to an elastomeric substrate. In\nthis article, we manufactured polydimethylsiloxane (PDMS)-encapsulated\nLIG piezoresistive strain sensors with a quasi-linear behavior and\na gauge factor of 111. The produced LIG was morphologically characterized\nvia Raman spectroscopy and scanning electron microscopy before and\nafter the electromechanical characterization and before and after\nthe LIG transfer to PDMS. The results from these analyses revealed\nthat the integrity of the material after the test was not affected\nand that the LIG volume in contact with the substrate increased after\ntransfer and encapsulation in PDMS, leading to the improvement of\nthe sensor performance. The sensors’ capability for measuring\nbend angles accurately was demonstrated experimentally, making them\nuseable in a wide range of applications for human body movement monitoring\nas well as for structural health monitoring. Regarding body monitoring,\na PDMS-encapsulated LIG sensor for knee bending angle detection was\nproposed. This device showed unaffected performance of 1500 cycles\nunder 8% uniaxial deformation and with response times in the range\nof 1–2 s