• Journal of Sensor Science and Technology
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• v.14 no.4
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• pp.225-230
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• 2005

This paper describes a novel tip position sensor made of a triangularly shaped piezoelectric PVDF (polyvinylidene fluoride) film for a cantilever beam. Due to the boundary condition of the cantilever beam and the spatial sensitivity function of the sensor, the charge output of the sensor is proportional to the tip position of the beam. Experimental results with the PVDF sensor were compared with those using two commercially available position sensors: an inductive sensor and an accelerometer. The resonance frequencies of the test beam, measured using the PVDF sensor, matched well with those measured with the two commercial sensors and the PVDF sensor also showed good coherence over wide frequency range, whereas the inductive sensor became poor above a certain frequency.

• Journal of Sensor Science and Technology
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• v.28 no.4
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• pp.205-215
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• 2019

A flexible polyvinylidene fluoride (PVDF)/polydimethylsiloxane (PDMS) composite prototype with high piezoelectricity and force sensitivity was constructed, and its huge potential for applications such as biomechanical energy harvesting, self-powered health monitoring system, and pressure sensors was proved. The crystallization, piezoelectric, and electrical properties of the composites were characterized using an X-ray diffraction (XRD) experiment and customized experimental setups. The composite can sustain up to 100% strain, which is a huge improvement over monolithic PVDF fibers and other PVDF-based composites in the literature. The Young's modulus is 1.64 MPa, which is closely matched with the flexibility of the human skin, and shows the possibility for integrating PVDF/PDMS composites into wearable devices and implantable medical devices. The $300{\mu}m$ thick composite has a 14% volume fraction of PVDF fibers and produces high piezoelectricity with piezoelectric charge constants $d_{31}=19pC/N$ and $d_{33}=34pC/N$, and piezoelectric voltage constants $g_{31}=33.9mV/N$ and $g_{33}=61.2mV/N$. Under a 10 Hz actuation, the output voltage was measured at 190 mVpp, which is the largest output signal generated from a PVDF fiber-based prototype.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2011.05a
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• pp.35-36
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• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.509-510
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.709-710
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• 2010

• Polymer(Korea)
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• v.28 no.5
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• pp.361-366
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• 2004

The poling characteristics of PVDF (poly(vinylidene fluoride)) film was investigated by measuring the electric voltage generated by the external load for the distributed tactile sensor applications. The poling conditions for the PVDF films were controlled by changing temperature and electric field, and the resulting crystal structure of the $\beta$-phase crystal was confirmed by FT-IR, DSC, and XRD experiments. The $\beta$-phase crystal was increased with the poling temperature and poling voltage, and subsequently the permittivity of the Poled PVDF films was increased. Finally, the prototype tactile sensor was tested by a 8 $\times$ 8 may circuit exhibiting high voltage signal for the highly poled PVDF films.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.390-390
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• 2000

This research is the development of a skin-type tactile sensor for service robot using PVDF film for the detection of the contact state. The Prototype of the tactile sensor which has 8$\times$8 taxels was fabricated using PVDF film In the fabrication procedure of the sensor, the electrode patterns and common electrode of the thin conductive tape were attached to the both side of the 28 micro meter thickness PVDF film using conductive adhesive. The sensor was covered with polyester film for insulation and attached to the rubber base for making stable structure. The signals of a contact pressure to the tactile sensor were sensed and processed in the DSP system in which the signals were digitized and filtered. Finally, the signals were integrated for taking the force profile. The processed signals of the output of the sensor were visualized in PC, the shape and force distribution of the contact object were obtained. The reasonable performance for the detection of contact state was verified through the experiment.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.125-128
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• 2003

Low-velocity impact damage is a major concern in the design of structures made of composite materials, because impact damage is hidden inside and cannot be detected by visual inspection. The piezoelectric thin film sensor can be used to detect variations in structural and material properties for structural health monitoring. In this paper, the PVDF and PZT sensors were used for monitoring impact damage initiation in Gr/Ep composite panel to illustrate this potential benefit. A series of impact test at various impact energy by changing impact mass and height is performed on the instrumented drop weight impact tester. The wavelet transform(WT) is used to decompose the piezoelectric sensor signals in this study. Test results show that the particular waveform of sensor signals implying the damage initiation and development are detected above the damage initiation impact energy. And it is found that both PZT and PVDF sensors can be used to detect the impact damage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.151-157
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• 2018

Among the various sensors for measuring traffic, PVDF (polyvinylidene fluoride) piezoelectric sensors are used to classify vehicles because they can detect the axle of the vehicle. Piezoelectric sensors are embedded in road pavements and are always exposed to traffic loads and environmental loads. Therefore, the life expectancy is very short, less than 6 years. Traffic control is essential for reinstallation and data collection is interrupted during the failure period. The lifespan will increase if the sensor installation depth is increased. In this study, the sensor signal output was analyzed with a variable depth of sensor installation to verify the possibility of deeper installation. Furthermore, various parameters, such as the weight and speed, were analyzed. The wheel load is applied using APT. As a result, the MSI BL sensor output signal is higher than 100mV when installed at 3cm, which is reliable. If the location of the sensor is deeper in the pavement, the expected lifetime of the sensor is also increased. On the other hand, the MSI cable was found to be less than 100mV at the shallowest depth of 1cm, making it impossible for field applications.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.364-372
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• 2006

In this paper, we present a finger tip tactile sensor which can detect contact normal force as well as slip. The sensor is made up of two different materials, such as polyvinylidene fluoride (PVDF) known as piezoelectric polymer, and pressure variable resistor ink. In order to detect slip on the surface of the object, two PVDF strips are arranged along the normal direction in the robot finger tip and the thumb tip. The surface electrode of the PVDF strip is fabricated using silk-screening technique with silver paste. Also a thin flexible force sensor is fabricated in the form of a matrix using pressure variable resistor ink in order to sense the static force. The developed tactile sensor is physically flexible and it can be deformed three-dimensionally to any shape so that it can be placed on anywhere on the curved surface. In addition, a tactile sensing system is developed, which includes miniaturized charge amplifier to amplify the small signal from the sensor, and the fast signal processing unit. The sensor system is evaluated experimentally and its effectiveness is validated.