###### Abstract  
The development of gas sensors for detecting alcoholic vapors with a low molecular weight is essential for environmental protection, industrial process control, and the monitoring of the living atmosphere in daily life to avoid health problems in human beings. Here, poly (lactic acid) (PLA)/shellac/PLA sandwich-structural membranes were fabricated via an electrospinning approach and the interaction with alcoholic vapors with a low molecular weight was investigated. It was found that the PLA/shellac/PLA sandwich-structural membrane exhibited fast response to the alcoholic vapors with low molecular weight, especially for methanol vapor. After being treated with alcohol vapor with a low molecular weight, the PLA/shellac/PLA sandwich-structural membrane could change its transmission in a short time (\(\sim\)5 s) and with a concentration of 10 wt% of methanol (ethanol) in water. In the meantime, the PLA/shellac/PLA sandwich-structural membrane can hopefully be potentially used again after evaporating the alcoholic vapor at an elevated temperature. s 2019 9 5419 20  
metabolites have a stimulating effect on the respiratory tract and gastrointestinal mucosa. The vapor can strongly stimulate conjunctiva of the eye. Methanol may also cause toxic effects on vascular nerves, resulting in vasospasm, forming blood stasis and bleeding. In severe cases, due to the cerebral blood circulation disorders and direct effects on the fine nerve sputum, tissue organic lesions may occur. Similarly, ethanol vapor is also harmful to the human body. Exposure to ethanol vapor may cause health problems such as a headache, lethargy, eye irritation, liver damage and difficulty in breathing [6]. Moreover, ethanol inhibits the high activity of the cerebral cortex. Exposure to high concentrations of ethanol vapor also inhibits peripheral nerves. Therefore, it is necessary to develop a sensor for detecting alcoholic vapor concentration with a lower molecular weight. [PERSON] et al. demonstrated an ethanol vapor sensor using a ZnO nanoparticle film as a coating layer on a SOI (silicon-on-insulator) micro-ring resonator with a radius of 5 \(\upmu\)m at room temperature. The partial coating on the ring resonator was prepared using a colloidal suspension of ZnO nanoparticles having a diameter of about 3 nm [7]. [PERSON] et al. reported that the TiO\({}_{2}\) nanobelts were prepared using a hydrothermal treatment, and their surfaces were processed by surface engineering, including surface roughening using an acidic etching process, forming an Ag-TiO\({}_{2}\) heterojunction on the surface of the TiO\({}_{2}\) nanobelts by photoreduction. These researchers managed to test the performance of all samples in ethanol vapor atmosphere and to compare that with the conductivity measurements at a series of temperatures [8]. [PERSON] et al. worked out a method of stimulating ITO (indium-tin-oxide) film recrystallization by depositing an ITO film on an ultra-thin Cu stimulator, which was used to improve the sensitivity, selectivity and minimum detection limit of a methanol sensor operated at room temperature [9]. However, most alcoholic vapor sensors with low molecular weights produced by inorganic materials, metallic oxides and their composites are fabricated using complex processes with high costs, and they cannot work at room temperature in particular. Moreover, these materials are not biodegradable after use, leading to unnecessary environmental pollution. Therefore, better measures should be developed to introduce a new sensor for alcoholic vapor with a low molecular weight through a new approach that is facile, of low cost, and biodegradable, and potentially that can be embedded in clothing. The electrospinninging process is simple and easy to use.