Abstract
Graphene with atomic thickness possesses excellent mechanical and electrical properties, which hold great potential for high performance pressure sensing. The exposed electron of graphene is always cross-sensitive to any pollution absorbed or desorbed on the surface, from which the long-term stability of the graphene pressure sensor suffers a lot. This is one of the main obstacles towards graphene commercial applications. In this paper, we utilized polymethylmethacrylate (PMMA)/graphene heterostructure to isolate graphene from the ambient environment and enhance its strength simultaneously. PMMA/graphene pressure sensors, with the finite-depth cavities and the through-hole cavities separately, were made for comparative study. The through-hole device obtained a comparable sensitivity per unit area to the state of the art of the bare graphene pressure sensor, since there were no leaking cracks or defects. Both the sensitivity and stability of the through-hole sensor are better than those of the sensor with 285-nm-deep cavities, which is due to the sealed gas effect in the pressure cavity. A modified piezoresistive model was derived by considering the pressure change of the sealed gas in the pressure cavity. The calculated result of the new model is consistent with the experimental results. Our findings point out a promising route for performance optimization of graphene pressure sensors.
Highlights
Graphene, as natural atomic material, is an ideal option as a sensing membrane of pressure sensors
To overcome with a 285-nm-deep cavity and through-hole cavity were designed on the same chip. The fabrication these problems, we introduced a polymer-assisted process flow is schematically depicted in Figure 1. graphene pressure sensor scheme where a thin poly-methylmethacrylate (PMMA)
The dark curve is the resistance of the PMMA/graphene pressure sensor reference commercial sensor
Summary
As natural atomic material, is an ideal option as a sensing membrane of pressure sensors. 2020, 11, 786processes bring a heavy load on the atomic graphene sheet To overcome these since the fabrication problems, we introduced a polymer-assisted graphene pressure sensor scheme where a thin polymethylmethacrylate (PMMA) film was used as both a supporting and sealing layer of the graphene piezoresistive effect, which makes the graphene both the membrane for pressure loading and the sheet [16]. Even though there are lots of similar works that followed [13,14,15], in reality, the graphene sensor lot from issues of low yield,PMMA/graphene membrane cracks,pressure and gas leakage, To studypressure the effect of thesuffers sealeda gas in the pressure cavity, sensors since the fabrication processes bring a heavy load on the atomic graphene sheet.
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