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Laser engraving is carried out on the both sides of PI film to achieve constant temperature gas monitor and early automatic self-alarm. [Display omitted] • The LIG IDEs serve gas sensor, and rectangular LIG is usable in dual-working mode. • The rectangular LIG provides a constant working temperature under a DC voltage. • The NO 2 monitor with heating condition overcomes the inability to desorb at RT. • Let the device emit an acoustic alarm once NO 2 concentration is beyond threshold. The increasingly serious air pollution problem makes the development of high-performance gas monitoring system extremely urgent. Especially for nitrogen dioxide (NO 2), which is harmful to both people and the environment. The combination of reliable real-time monitoring and early warning is of great significance yet less study. Here, we designed a laser-induced graphene (LIG)-based multi-functional NO 2 monitor and self-alarm (MMSA), in which a rectangle area is used as a dual-functional module to realize high-performance temperature condition and acoustic alarm by applying direct/alternating current voltage excitation source. The molybdenum disulfide (MoS 2) sensitive material works in concert with the LIG interdigital electrodes (IDEs), and the gas monitor achieves high sensitivity (86.81% for 5 ppm, and 22.90% for 250 ppb) and excellent recoverability, aided by the good electrothermal property of LIG, overcoming the dilemma of poor sensing performance of MoS 2 at room temperature (RT). To top it off, the thermoacoustic effect of the LIG could bring about an intuitional sound signal, and a proof-of-concept demonstrates the timely acoustic warning response of the MMSA to exceeded NO 2 concentrations. [ABSTRACT FROM AUTHOR]