In this work, a new method to enhance the sensing response of an ultrasonically catalyzed metal oxide gas sensor has been proposed and developed, in which pulse ultrasound is employed to enhance the redox reaction at the sensing surface. It is experimentally confirmed that with a proper pulse width, the negative effect of acoustic streaming on the ultrasonic enhancement process can be effectively suppressed. Comparing the steady responses of five target gases under the pulse and continuous ultrasound, respectively, it is found that the pulse ultrasound causes a better catalysis effect, and response enhancement (RE) by the pulse ultrasound with an optimal pulse width depends on the ultrasonic strength as well as the species and concentration of the target gas. For 2 ppm methanol, the RE by the pulse ultrasound is 50%, relative to the continuous ultrasound, when the pulse width, duty ratio, and working frequency are 0.4 ms, 50%, and 110.1 kHz, respectively. The optimal pulse width decreases when the ultrasonic strength increases and is not affected by the target gas species and concentration. The lower the target gas concentration, the larger the optimal RE caused by pulse ultrasound. Moreover, for a given pulse width, the interpulse time also affects the RE.

中文翻译：

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MOX 气体传感器基于脉冲超声的响应增强


在这项工作中，提出并开发了一种增强超声催化金属氧化物气体传感器传感响应的新方法，其中采用脉冲超声来增强传感表面的氧化还原反应。实验证实，在适当的脉冲宽度下，可以有效抑制声流对超声增强过程的负面影响。比较 5 种目标气体在脉冲超声和连续超声下的稳定响应，发现脉冲超声具有较好的催化效果，具有最佳脉冲宽度的脉冲超声的响应增强 （RE） 取决于超声强度以及目标气体的种类和浓度。对于 2 ppm 甲醇，当脉冲宽度、占空比和工作频率分别为 0.4 ms、50% 和 110.1 kHz 时，脉冲超声的 RE 相对于连续超声为 50%。当超声强度增加时，最佳脉冲宽度会减小，并且不受目标气体种类和浓度的影响。目标气体浓度越低，脉冲超声引起的最佳 RE 就越大。此外，对于给定的脉冲宽度，脉冲间时间也会影响 RE。