Fig. 1. Schematic of LIG preparation

Fig. 2. Optimal parameters for preparing LIG. (a) Pattern and path of laser scan (unit: mm); (b) laser marked image on pine wood with 3D image shown in upper-right corner; (c) relationship between LIG resistance and laser pulse frequency; (d) relationship between LIG resistance and vacuum chamber pressure; (e) relationship between LIG resistance and defocus distance; (f) relationship between LIG resistance and marking speed; (g) relationship between LIG resistance and marking time; (h) relationship between LIG width and laser power

Fig. 3. Characterization of sample. (a) SEM image of LIG (parameter: F＝10 kHz, P＝100 Pa, D＝4 mm, S＝100 mm·s^－1,M＝14, and L＝10 W); (b) local magnification of Fig. 3 (a); (c) Raman spectroscopy of LIG; (d) infrared spectra of LIG and pine wood

Fig. 4. Fabrication and test of pressure sensor. (a) Structure and size of resistance strain gauge; (b) physical map (parameter: F＝10 kHz，P＝100 Pa，D＝4 mm，S＝100 mm·s^－1，M＝14, and L＝10 W); (c) schematic of pressure sensor test system; (d) relationship between sensor resistance and load; (e) relationship between sensor resistance and unloading

Fig. 5. Dynamic test of pressure sensor. (a) Single response process; (b) 300 repetitive stress tests; (c) change of resistance under multiple cycle pressures

Fig. 6. Fabrication and test of temperature sensor. (a) Schematic of temperature sensor test system; (b) relationship between resistance and temperature (parameter: F＝10 kHz, P＝100 Pa, D＝4 mm, S＝100 mm·s^－1,M＝14, and L＝10 W); (c) overall strain analysis of sensor; (d) strain of strain gauge when loading 8 kg and heating 100 ℃

Fig. 7. Fabrication and test of integrated pressure and temperature sensor. (a) Model; (b) physical map (parameter: F＝10 kHz, P＝100 Pa, D＝4 mm, S＝100 mm·s^－1,M＝14, and L＝10 W); (c) schematic of test system; (d) test results of pressure (curved surface) and temperature(black dots)