PMMA/ 石墨烯异质压力传感器及传感特性分析

石墨烯具有优异机电性能和超大比表面积,其显著压阻效应可应用于高性能压力传感,为探索下一代超灵敏传感器开 辟新方向。 目前在研石墨烯压力传感器存在石墨烯悬空破损严重、成品率低等难题,其根源在于,石墨烯除胶释放过程应力过 载。 本文提出以 PMMA/ 石墨烯复合异质薄膜替代单层石墨烯的压力传感器新方案,设计 COMS 兼容新工艺,可实现传感器规 模化制备,成品率接近 100% 。 测试表明,本文传感器灵敏度高达 7. 42×10 -5 / kPa,优于与已报道结果。 提取传感器压力测量精 度约为 2. 6% ~ 3. 5% ,比国外禁运高性能压力传感器精度(0. 05% ~ 0. 01% FS)差近 2 个数量级,其主因在于测量系统电噪声及 受工艺污染石墨烯本征电阻噪声。 当前石墨烯压力传感器研究的重点应聚焦精度指标的提高,而不是片面追求灵敏度指标。

Pressure sensor based on PMMA / graphene hetero-film and its sensing characteristics

Graphene with atomic thickness has advantages of excellent electromechanical properties and super-large specific surface area. Combined with the significant piezoresistive effect, graphene opens up window for next generation of the ultra-sensitive pressure sensor. The main cause of the low-yield for graphene sensor made by the conventional fabrication process is analyzed to be the overloaded stress during its release process from the liquid. To solve this problem and improve the yield, a new pressure sensor scheme by using polymethylmethacrylate (PMMA) / graphene composite heterogeneous film (hetero-film) is proposed to replace the atomic graphene film. The corresponding fabrication process compatible with the traditional COMS process is designed and applied to sensor fabrication, which reaches a much higher yield and holds the hope for large-scale fabrication. The pressure sensing test shows that the sensitivity of the new graphene pressure sensor is up to 7. 42 × 10 -5 / kPa, which is comparable to the existing research. However, the extracted sensing precision is low to 2. 6% ~ 3. 5% in the full-scale range (FS), which is nearly 2 orders worse than the silicon-based high-performance pressure sensor (0. 05% ~ 0. 01% FS). The electrical noise of the measurement system and the intrinsic resistance noise of the polluted graphene may be the key root. This work suggests that more research on graphene pressure sensor should focus on the improvement of sensing precision indicator rather than the pursuit of sensitivity.