# Seoul National University ethanol sensor of five-metal oxide shows 5135% response at 50 ppm

- Published: 2026-11-15 10:41 UTC
- Section: Machines & Making › Electronics
- Tags: ethanol gas sensor, high-entropy oxide, chemoresistive sensor, InSnFeZnW oxide, sensor without precious metals, oxygen vacancies, d-band structure, Seoul National University, metal oxide semiconductor
- URL: https://realtech.media/news/rt-a6edbb220344dfdae318508e_seoul_national_university/

**A laboratory ethanol sensor made of a high-entropy oxide of In, Sn, Fe, Zn and W responds 7.9–12.6 times stronger than medium- and low-entropy oxides and has no precious metals.**

![Seoul National University ethanol sensor of five-metal oxide shows 5135% response at 50 ppm](https://realtech.media/media/2026/11/be78adf74b232f80.jpg)
*Наука 2.0*

Researchers at Seoul National University have developed an ethanol (C₂H₅OH) gas sensor based on a high-entropy oxide of five metals: indium, tin, iron, zinc and tungsten. The composition of the sensor and the electronic-structure mechanisms behind its operation are described in Advanced Science [1]. The material, (InSnFeZnW)Oₓ, is essentially a solid solution of five oxides, and none of the metals is precious [1]. This is a laboratory sensor; the authors compared it with oxide sensors of low and medium entropy.

## Response and kinetics

At 50 ppm ethanol and 300 °C, the response of the high-entropy sensor, measured as the change in resistance, was 5135%. The low-entropy oxide gave 408% and the medium-entropy oxide 654%, so the high-entropy response was about 12.6 and 7.9 times higher, respectively [1]. At this concentration the response time was 3 seconds, and the recovery time after ethanol removal was 73 seconds. According to calculations, the theoretical detection limit may start from 4.8 ppb.

The sensor kept its initial parameters for six months and operated repeatedly at 90% relative humidity, the authors report [1].

## Mechanism and limits

A single-metal oxide has a limited number of surface sites available for gas reactions, which makes it hard to raise sensitivity and selectivity at the same time. To check that all five metals occupy places in the crystal lattice and to explain the mechanism, the team used X-ray diffraction, Raman spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and other methods. The high-entropy oxide contains more chemisorbed oxygen and more oxygen vacancies than the low-entropy one, and entropy-driven shifts in the d-band structure strengthen the surface reaction pathway [1].

The optimal operating temperature is 300 °C, so further experiments will aim to lower it. The researchers also want to improve selectivity and resistance to changes in humidity. The project leader, Professor Chan Ho Won, said the team plans to explore other element combinations to make materials that respond selectively to substances besides ethanol, and to extend the work toward sensors that detect different gases.

## Sources

1. [Advanced Science](https://doi.org/10.1002/advs.75724)
2. [Наука 2.0](https://naukatv.ru/news/khimiki_sdelali_sverkhchuvstvitelnyj_alkosensor_bez_dragmetallov)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-a6edbb220344dfdae318508e_seoul_national_university/