Fig. 1. Number of references related to “laser” and “sensor” in past 20 years retrieved from Web of Science database

Fig. 2. Preparation and modification of metals, metal oxides, graphene, and other materials based on interaction of laser and material. Fabricated sensors can be applied to detection for signals of ultraviolet, gas, humidity, temperature, and strain/pressure, biological signals, and environmental signals

Fig. 3. Three laser processing modes. Heating:sintering and annealing for materials; delamination: removal or layering of partial materials by laser cutting or stripping; reaction: synthesizing new material and realizing material modification and microstructure regulation

Fig. 4. Laser heating induced nanowire welding and laser induced delamination. (a) Schematic illustration of plasmonic laser nanowelding process^[18]; (b) schematic diagrams and SEM images of Ag nanowires (NWs) before and after laser welding^[20]; (c) laser welding for Ag and ZnO NWs when ZnO NWs are on top of Ag NWs and when Ag NWs are on top of ZnO NWs^[23]

Fig. 5. Graphene and its composites prepared by laser processing. (a) Schematic illustration of preparation of graphene bulks and its functional composites^[47]; (b) synthesis process of LIG on PI substrate and SEM image of LIG patterned into owl shape; (c) SEM image of LIG film and cross-sectional SEM image of LIG film on the PI substrate^[48]; (d) LRG pattern formed on bread, pine wood, tissue paper, card

Fig. 6. UV sensors. (a) SEM images of ZnO nanoparticles (NPs) before and after nanosecond pulsed laser irradiation treatment (inset: particle size distribution histogram)^[74]; (b) schematic diagram of highly oriented assembly of ZnO NWs via laser direct writing technology; (c) schematic diagram and optical micrograph of ZnO NW-based UV photodetector based on ZnO NWs after highly oriented assembly^[75]; (d)

Fig. 7. Gas sensors. (a) SEM of PbO nanosheet. Inset: TEM image of PbO nanosheet; (b) schematic illustration of chemical trapping strategy^[86]; (c) schematic illustration of gas-sensing device and SEM image of mesocrystal CuO; (d) real-time gas-sensing response of different CuO to ethanol^[88]; (e) selectivity of pure ZnO and Au-ZnO nanospheres for various gases; (f) scheme of gas sensing mechanism of Au-Z

Fig. 8. Humidity sensors. (a) Schematic illustration of interaction between water molecules and GO nanosheets^[102]; (b) illustration of two-beam-laser interference reduction of GO film^[103]; (c) prototype demonstration of e-skin used for simulation of noncontact sensing properties of human skin^[102]; (d) schematic illustration of fabrication process of

Fig. 9. Temperature sensors. (a) Schematic of temperature sensor fabrication via monolithic laser reductive sintering; (b) artificial skin of model hand covered with sensor; (c) integrated sensor array; (d) temperature sensors attached at various facial positions^[109]; (e) photo of LIG temperature sensor on leaf and test signals of sensor; (f) integration of electronic devices on leaf, including temperature sensor, supercapacitor, and conductive circuit

Fig. 10. Fabrication of planar pressure/strain sensors by laser. (a) Graphene strain sensor prepared by ultraviolet laser^[117]; (b) structural diagram of graphene pressure sensor^[119]; (c) variation of relative resistance of sensor with external pressure along z direction; (d) cross-section illustration of single sensor which is quite similar to a mechanical triode^{[Download full size}

Fig. 11. Face to face pressure/strain sensors. (a) Two identical LIGs are assembled face to face into a sensor^[129]; (b) two identical LIGs are assembled in different directions to form sensor^[131]; (c) asymmetric sensor is assembled from LIG film and LIG interdigitated electrode^[132]; (d) asymmetric sensor is assembled from transparent Ag nanowire membr

Fig. 12. Acoustic sensors. (a) Schematic diagram of acoustic sensor preparation; (b) schematic diagram and real person test diagram of overall concept of self-cleaning anti-interference voice recognition system^[136]; (c) one-step fabrication process of LIG; (d) LIG has ability of emitting and detecting sound in one device; (e) LIG artificial throat can detect movement of throat and generate controllable sound. For tester wearing LIG artificial throat, hi

Fig. 13. Preparation of biomolecular sensors. (a) Illustration of SERS sensor for detection of methylated DNA and its derivatives; (b) illustration and SEM images of Ag NPs array before and after graphene wrapping. From left to right: Ag array before graphene wrapping, graphene covered Ag array, and laser wrapped graphene-Ag array^[142]; (c) schematic illustration of fabrication procedure of Ag NPs@RGO SERS biochip^[14

Fig. 14. Sweat sensors. (a) Schematic diagram of wearable sweat sensor; (b) multiple functions of sensor. Temperature sensor and electrochemical sensor are used for detection of uric acid and tyrosine and estimation of sweat rate; pressure sensor is used for monitoring of heart rate, respiration rate, and so on; (c) photograph of flexible lab-on-skin patch^[150]; (d) illustration of laser-engraving process of graphene sensor and picture of graphene sensor

Fig. 15. Preparation of heavy metal ion and pollutant sensor. (a) Schematic illustration of preparation of photoelectrode with laser induced CdS and graphene composites on ITO glass^[158]; (b) schematic diagram of bisphenol A sensor^[159]; (c) schematic diagram of LDW electrode on the PI^[160]; (d) large size preparation of self-supporting LIG paper; (e) sc

Fig. 16. Paper-based sensors prepared by laser. (a) Schematic diagram of preparation process of electrochemical sensor with multiple sensing functions^[165]; (b) photograph of pattern on paper obtained by LDW folded into a three dimensional structure; (c) process diagram for preparation of Mo₃C₂-graphene composites on paper^[166]