On some occasions, such as new energy clinics, monitoring the trace hydrogen at the ppb level is necessary. The traditional resistive hydrogen sensors based on the Pd alloys are very difficult to realize such an extremely low detection limit. To achieve a detection limit at the ppb level and also ensure good stability, a MEMS hydrogen sensor was designed in a suspended Wheatstone bridge structure, with all four resistive arms defined on a sputtered Pd–Au alloy thin film. For the Wheatstone bridge sensor, absolute response (R_a) and relative response (R_s) are defined to describe the sensitivity of the sensor, and the effect of annealing temperature on baseline drift is investigated using the baseline zero drift parameter (DBZD). By testing the sensors across a hydrogen concentration range of 20 ppb to 3 v/v%, the optimal annealing temperature (250 °C) and operating temperature (60 °C) were identified. Under these conditions, the sensor exhibited a detection limit as low as 20 ppb with a power consumption of only 4.6 mW. At the same time, the response and recovery times of the sensor were 6 and 19 s, respectively, toward 3 v/v% hydrogen. After testing over a 100-day period, R_a fluctuated only 0.0026%, indicating that the hydrogen sensor had good long-term stability for low-concentration detection. More results also showed that the sensor has good repeatability, selectivity, and humidity resistance. With the wide measurement range (20 ppb to 3 v/v%), the sensor has the potential to meet hydrogen detection requirements in multiple scenarios.

中文翻译：

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惠斯通电桥 MEMS 氢气传感器，具有基于钯金合金的 ppb 级检测限


在某些情况下，例如新能源诊所，有必要监测 ppb 级的痕量氢。基于 Pd 合金的传统电阻式氢传感器很难实现如此极低的检测限。为了达到 ppb 级的检测限并确保良好的稳定性，在悬浮惠斯通电桥结构中设计了一个 MEMS 氢传感器，所有四个电阻臂都定义在溅射的 Pd-Au 合金薄膜上。对于惠斯通电桥传感器，定义了绝对响应 （R_a） 和相对响应 （R_s） 来描述传感器的灵敏度，并使用基线零点漂移参数 （DBZD） 研究了退火温度对基线漂移的影响。通过在 20 ppb 至 3 v/v% 的氢气浓度范围内测试传感器，确定了最佳退火温度 （250 °C） 和工作温度 （60 °C）。在这些条件下，传感器的检测限低至 20 ppb，功耗仅为 4.6 mW。同时，传感器对 3 v/v% 氢气的响应和恢复时间分别为 6 秒和 19 秒。经过 100 天的测试，R_a 仅波动了 0.0026%，表明氢传感器在低浓度检测方面具有良好的长期稳定性。更多结果还表明，该传感器具有良好的可重复性、选择性和耐湿性。该传感器具有较宽的测量范围（20 ppb 至 3 v/v%），有可能满足多种情况下的氢气检测要求。