EHD Inkjet Printing Machine: In situ preparation of SnO2/Pd@TiO2 bilayer sensor for highly sensitive and fast detection of H2S based on electrohydrodynamic jet printing

A micro double-layer H2S sensor was designed and fabricated using EHD jet printing technology, which has excellent sensitivity, fast response, and long-term stability.

Research background

Hydrogen sulfide (H2S) is a common flammable and toxic environmental pollutant, as well as a nerve agent. Traditional metal oxide semiconductor sensing films have a single-layer structure, and currently reported H2S sensors often cannot meet the requirements of high sensitivity, fast response, and long-term stability simultaneously, which limits their practical applications in environmental and health monitoring.

Research methods

The study used EHD jet printing technology to successfully prepare a SnO2/Pd@TiO2 basic microsensorSnO2/Pd@TiO2 with a double-layer structure and a stable transition layer by precisely controlling the stacking of ink and printing conditions.By optimizing the printing frequency and material addition amount, the sensitivity and response performance of the sensor have been improved. The effectiveness of the sensor in H2S detection has been verified through experiments.(Represent the sensor asmSnO2/nPdX@TiO2 ,M and n represent the number of prints for the bottom and cover layers, respectively, and X represents the photoreduction time (min) of Pd.)

Optimize printing frequency and material addition amount:

Study the printing frequency of the underlying SnO2, whether TiO2 NPs are added, and the effect of adding different contents of Pd NPs to TiO2 NPs on the sensor response value.

High sensitivity:

Overall, the double-layer sensor(8SnO2/4Pd30@TiO2)The response of the sensor is 6.8 times that of the single-layer sensor (12SnO2), and it has a significant response to different concentrations of H2S.

Fast response:

8SnO2/4Pd30@TiO2The response time and recovery time of the sensor for 2 ppm H2S are 7 seconds and 45 seconds, respectively.

Long term stability:

After 270 days of intermittent measurement, the sensor's response to 2ppm H2S only decreased by 10.6%, and the response time and recovery time increased by 3 seconds and 21 seconds, respectively.

Conclusion 

The H2S sensor is manufactured using EHD jet printing technology, using common and easily obtainable materials, and has excellent sensitivity, rapid response, and long-term stability. This work also demonstrates the feasibility of using EHD jet printing technology to manufacture multi-layer structure adjustable sensors, and the design ideas involved can be further extended to the manufacturing of other gas sensing devices.

Paper Link:https://doi.org/10.1016/j.snb.2024.135591