MEMS piezo-resistive force sensor based on DC sputtering deposited amorphous carbon films

Ma, Xin; Tong, Xiaoshan; Guo, Peng; Zhao, Yue; Li, Hanchao; Chen, Rende; Wang, Aiying

doi:10.1016/j.sna.2019.111700

Cited by 16 publications

(11 citation statements)

References 31 publications

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“…The measured gauge factors ( GF s) are in the range between 2.0 and 3.5 depending on the pyrolysis temperature. These GF s are close to those of metals and similar to the GF s measured for nonoptimized a-C or single-layered graphene 4 , 19 , 20 . As suggested by the works of Dai et al .…”

Section: Discussionsupporting

confidence: 80%

“…Carbon allotropes, including graphite 13 – 15 , carbon nanotubes (CNTs) 16 – 18 , amorphous carbon (a-C) 4 , 19 , graphene 20 , 21 , and nanofoams 7 , have already been studied as piezoresistive materials. The diverse mechanical and electrical properties of structural allotropes are due to the different sp, sp 2 , and sp 3 hybridized bonds, thus enabling a variety of sensor applications.…”

Section: Introductionmentioning

confidence: 99%

“…Zhao and Bai presented a graphite nanoplatelet/CNT hybrid nanocomposite in a polymer matrix to implement highly sensitive piezoresistors 18 . a-C thin films deposited by sputtering have been applied in MEMS force sensors, in which the GF can be tuned by the ratio of sp 2 /sp 3 varying the DC bias voltage during sputtering 4 , 19 . The GF of graphene has been evaluated by transferring it to a silicon nitride membrane and used as a pressure sensor 20 .…”

Section: Introductionmentioning

confidence: 99%

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SU-8 cantilever with integrated pyrolyzed glass-like carbon piezoresistor

et al. 2022

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Glass-like carbon (GC) is a nongraphitizing material composed entirely of carbon atoms produced from selected organic polymer resins by controlled pyrolysis in an inert atmosphere. The GC properties are a combination of the properties of glass, ceramic, and graphite, including hardness, low density, low thermal conductivity, high chemical inertness, biocompatibility, high electrical conductivity, and microfabrication process compatibility. Despite these unique properties, the application of GC in mechanical sensors has not been explored thus far. Here, we investigate the electrical, structural, and chemical properties of GC thin films derived from epoxy-based negative photoresist SU-8 pyrolyzed from 700 to 900 °C. In addition, we fabricated microGC piezoresistors pyrolyzed at 700 and 900 °C and integrated them into nonpyrolyzed SU-8 cantilevers to create microelectromechanical systems (MEMS) mechanical sensors. The sensitivities of the GC sensor to strain, force, surface stress, and acceleration are characterized to demonstrate their potential and limits for electromechanical microdevices.

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Section: Discussionsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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SU-8 cantilever with integrated pyrolyzed glass-like carbon piezoresistor

et al. 2022

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“…More details about the film deposition technique can be referred from our previous work. 26 To obtain a higher adhesion strength, the PDMS substrate was first etched by Ar + plasma for 60 min at a pulsed substrate bias voltage of −450 V and the working pressure was 1.1 Pa, which also hardened the PDMS surface. 27 During the subsequent a-C deposition, Ar gas (a flow rate of 65 sccm) was introduced into the chamber and ignited the sputtering of the graphite target with a working pressure of 0.3 Pa and a DC power at 2.1 kW.…”

Section: Methodsmentioning

confidence: 99%

Residual Compressive Stress Enabled 2D-to-3D Junction Transformation in Amorphous Carbon Films for Stretchable Strain Sensors

Guo

Tong

et al. 2020

ACS Appl. Mater. Interfaces

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Usually, two-dimensional (2D) flexible strain sensors based on cracks have very high sensitivities but small measuring ranges, while the three-dimensional (3D) ones behave in the opposite way. Here, by utilizing the large residual compressive stress of an amorphous carbon (a-C) film and the flexibility of polydimethylsiloxane (PDMS), we developed a facile and economic strategy to fabricate a high-sensitive a-C/PDMS stretchable strain sensor. Results showed that for the first time, the a-C film ranging from 25 nm to 1 μm changed the shape and orientation of conductive scales, as well as made a one-step 2D-to-3D electrical junction transformation in integrated sensors. In particular, the sensor with a 1 μm thick a-C film exhibited the best comprehensive performance, displaying a maximum gauge factor of 746.7 and strain range up to 0.5. However, the linearity decreased slightly as the strain range went beyond 0.43. Additionally, the sensor showed a satisfactory repeatability for 5000 cycles, together with excellent time and temperature drift performances at zero position of 75 ppm full scale (FS) and 25 ppm FS•°C −1 in the range of −20 to 155 °C, respectively. The sensor has large potentials for wearable devices used in the monitoring of various human motions and physiological signals.

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“…(7)(8)(9) The latter relies on the development of new materials and new MEMS processes to improve sensor sensitivity by replacing the traditional doped resistance with emerging materials such as polymer composite nanomaterials, graphene, and amorphous carbon films. (10,11) In contrast, because changing the sensitive structure does not depend on the development of new materials, it is more suitable for the development of high-performance accelerometers. (12) The incorporation of stress concentration slots into the sensitive structure was proved effective for enhancing the sensitivity of a sensor.…”

Section: Introductionmentioning

confidence: 99%