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皮秒雷射直寫石墨烯撓性基板於應變感測之研究
Other Title
Study of Picosecond Laser Direct-Writing Flexible Graphene for Strain Sensors
Type
thesis
Date Issued
2016-07-21
Author(s)
鄭楙弘
Advisor
歐耿良
Subjects
系所名稱：生醫材料暨組織工程研究所
Description
學位別：碩士
語文別：英文
指導教授：歐耿良
共同指導教授：
口試委員：劉沖明;陳錦松
中文關鍵字：石墨烯;應變規;雷射直寫
英文關鍵字：graphene;strain gauge;laser direct writing
語文別：英文
指導教授：歐耿良
共同指導教授：
口試委員：劉沖明;陳錦松
中文關鍵字：石墨烯;應變規;雷射直寫
英文關鍵字：graphene;strain gauge;laser direct writing
Abstract
Background
Strain gauge technology has been developed and applied in various fields in the last few years. The sensor material of strain gauge is one of the key components of its function and sensitivity performance. Successful applications of graphene have been announced and discussed. Graphene, a known material with the smallest resistivity up to date, could be valuable for developing new strain gauges.
Aims
To develop a new strain sensor based on graphene material and to compare with current commercial technology.
Material and Methods
Two kinds of material were selected: graphene thin film coated on a flexible substrate, such as chemical vapor deposition (CVD) graphene, and Poly (3,4-ethylenedioxythiophene):Polystyrenesulfonate/graphene (PEDOT:PSS/graphene). We used picosecond laser direct-writing method to scribe the graphene material into the designed shape in normal uniaxial direction as strain gauge. Before implementing the laser direct-writing processes on a graphene specimen, material parameters of graphene were examined. Spectrophotometry was used to measure light reflectance and transmittance of graphene specimen. Raman spectroscopy confirmed the purity of material. Atomic force microscope (AFM) was used to observe the surface roughness. Many different combinations of laser parameters were tested for laser direct-writing on the graphene specimens. The best combination of laser process parameters was developed. After laser processing, optical microscope, laser scanning confocal microscopy and scanning electron microscopy were used to observe the surface morphology and inspect the scribing effect of the conducting circuit. Various stresses were applied on the graphene and the deformation of the material was observed. When the conductors deformed, the resistance values was changed. We recorded the changes in stress and resistance value, and calculated the strain coefficient of the graphene strain gauges. We determined the stress by measuring the resistance value on the strain gauges.
Results
Absorbance value at 532 nm was 10.54% of light. In the study, picosecond laser system was selected. The best parameters of the scan speed, the laser power and the pulse repetition were 300 mm/sec, 0.76 W and 300 kHz, respectively. The processed specimen of the best parameters combination had the smoothest side at scraped area and the laser distance was approximately 0.02 mm.
The stress test result of graphene specimens, evaluated with commercial strain gauge, indicated that the graphene-based strain gauge could be used to measure the stress.
Conclusions
Being the smallest resistivity material, graphene has potentials to be used to improve the sensitivity of strain gauges. To investigate the measure efficiency of the new strain gauge using graphene as the sensor material, we proposed to measure the necessary physical quality testing and laser cutting parameters of the graphene. Some of the preliminary testing results in this study such as Raman analysis, transparent analysis and AFM measurement demonstrated the high quality of the graphene specimens. We conducted laser direct-writing of graphene specimens using feasible parameters. The stress test of this study demonstrated that we developed and evaluated the new product of graphene based strain gauge.
Strain gauge technology has been developed and applied in various fields in the last few years. The sensor material of strain gauge is one of the key components of its function and sensitivity performance. Successful applications of graphene have been announced and discussed. Graphene, a known material with the smallest resistivity up to date, could be valuable for developing new strain gauges.
Aims
To develop a new strain sensor based on graphene material and to compare with current commercial technology.
Material and Methods
Two kinds of material were selected: graphene thin film coated on a flexible substrate, such as chemical vapor deposition (CVD) graphene, and Poly (3,4-ethylenedioxythiophene):Polystyrenesulfonate/graphene (PEDOT:PSS/graphene). We used picosecond laser direct-writing method to scribe the graphene material into the designed shape in normal uniaxial direction as strain gauge. Before implementing the laser direct-writing processes on a graphene specimen, material parameters of graphene were examined. Spectrophotometry was used to measure light reflectance and transmittance of graphene specimen. Raman spectroscopy confirmed the purity of material. Atomic force microscope (AFM) was used to observe the surface roughness. Many different combinations of laser parameters were tested for laser direct-writing on the graphene specimens. The best combination of laser process parameters was developed. After laser processing, optical microscope, laser scanning confocal microscopy and scanning electron microscopy were used to observe the surface morphology and inspect the scribing effect of the conducting circuit. Various stresses were applied on the graphene and the deformation of the material was observed. When the conductors deformed, the resistance values was changed. We recorded the changes in stress and resistance value, and calculated the strain coefficient of the graphene strain gauges. We determined the stress by measuring the resistance value on the strain gauges.
Results
Absorbance value at 532 nm was 10.54% of light. In the study, picosecond laser system was selected. The best parameters of the scan speed, the laser power and the pulse repetition were 300 mm/sec, 0.76 W and 300 kHz, respectively. The processed specimen of the best parameters combination had the smoothest side at scraped area and the laser distance was approximately 0.02 mm.
The stress test result of graphene specimens, evaluated with commercial strain gauge, indicated that the graphene-based strain gauge could be used to measure the stress.
Conclusions
Being the smallest resistivity material, graphene has potentials to be used to improve the sensitivity of strain gauges. To investigate the measure efficiency of the new strain gauge using graphene as the sensor material, we proposed to measure the necessary physical quality testing and laser cutting parameters of the graphene. Some of the preliminary testing results in this study such as Raman analysis, transparent analysis and AFM measurement demonstrated the high quality of the graphene specimens. We conducted laser direct-writing of graphene specimens using feasible parameters. The stress test of this study demonstrated that we developed and evaluated the new product of graphene based strain gauge.