Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2015 Jan 20:5:7887.
doi: 10.1038/srep07887.

Highly sensitive and multifunctional tactile sensor using free-standing ZnO/PVDF thin film with graphene electrodes for pressure and temperature monitoring

James S Lee  1 , Keun-Young Shin  1 , Oug Jae Cheong  1 , Jae Hyun Kim  2 , Jyongsik Jang  1
Affiliations

Highly sensitive and multifunctional tactile sensor using free-standing ZnO/PVDF thin film with graphene electrodes for pressure and temperature monitoring

James S Lee et al. Sci Rep. .

Abstract

We demonstrate an 80-μm-thick film (which is around 15% of the thickness of the human epidermis), which is a highly sensitive hybrid functional gauge sensor, and was fabricated from poly(vinylidene fluoride) (PVDF) and ZnO nanostructures with graphene electrodes. Using this film, we were able to simultaneously measure pressure and temperature in real time. The pressure was monitored from the change in the electrical resistance via the piezoresistance of the material, and the temperature was inferred based on the recovery time of the signal. Our thin film system enabled us to detect changes in pressure as small as 10 Pa which is pressure detection limit was 10(3)-fold lower than the minimum level required for artificial skin, and to detect temperatures in the range 20-120 °C.

PubMed Disclaimer

Figures

Figure 1
Figure 1. (a) Schematic diagram and (b) a photograph of the device consisting of the ZnO/PVDF composite film and rGO electrodes.
Figure 2
Figure 2
(a) AFM image of the exfoliated GO solution. (b) XPS spectrum with fitted lines of the pristine and rGO solution for C–C, C–O and C = O bonds. (c) Raman spectra of the rGO electrodes.
Figure 3
Figure 3
SEM images of (a) the ZnO nanorods and (b) the ZnO nanodisks. (c) XRD spectra to investigate the crystal structure of the ZnO nanorods and disks.
Figure 4
Figure 4
(a) FTIR spectra of PVDF film fabricated as part of this work, and a commercially available PVDF film. The crystalline phases are indicated. (b) The permittivity and losses of the tactile sensor fabricated with PVDF and different ZnO nanostructures, as well as the PVDF thin film and the commercially available PVDF thin film.
Figure 5
Figure 5. The change in resistance of the pristine PVDF, and the PVDF/ZnO composite films.
(a) In response to an applied pressure of 30 Pa, showing the response time. (b) The sensitivity of the films at 20°C, using various Pt weights. (c) The response and (d) recovery times of the PVDF film, the ZnO nanodisk/PVDF film, and the ZnO nanorod/PVDF with various pressures.
Figure 6
Figure 6
(a) The spatial variation in the change in resistance. The effective area of fabricated device are 6 × 6 cm2. (b) The ZnO nanorod/PVDF film exhibited a higher pressure sensitivity than (c) the ZnO nanodisk/PVDF film. The film was divided into 144 regions (0.5 × 0.5 cm2) and Pt weights were used to apply a pressure of 30 Pa at each division, one at a time.
Figure 7
Figure 7
(a) The output resistance of the PVDF/ZnO nanorod device at various temperatures, 20, 70, and 120°C, under constant pressure of 30 Pa in the center of device. (b) The response to different pressures and (c) the recovery time at various temperatures.
Figure 8
Figure 8. The relationship between external pressure and the temperature of the object placed on the device to induce a pressure response.
(a) The change in the resistance and recovery time. (b) Pseudocolor plots showing the applied pressure on the PVDF/ZnO nanorod film. (c) The response to impact of a droplet with an unknown temperature. (d) The recovery time shows that the temperatures of the droplets were 20°C and 80°C, and the pressure was 90 Pa.
See this image and copyright information in PMC

References

    1. Pang C. et al. Flexible and highly sensitive strain-gauge sensor using reversible interlocking of nanofibres. Nature Mater. 11, 795–901 (2012). - PubMed
    1. Pecora A., Maiolo L., Maita F. & Minotti A. Flexible PVDF-TrFE pyroelectric sensor driven by polysilicon thin film transistor fabricated on ultra-thin polyimide substrate. Sensor Actuat. A-Phys. 185, 39–43 (2012).
    1. Hammock M. L. et al. 25th Anniversary Article: The Evolution of Electronic Skin (E-Skin): A Brief History, Design Considerations, and Recent Progress. Adv. Mater. 25, 5997–6038 (2013). - PubMed
    1. Lee J. S., Shin K.-Y., Kim C. & Jang J. Enhanced frequency response of a highly transparent PVDF–graphene based thin film acoustic actuator. Chem. Commum. 49, 11047–11049 (2013). - PubMed
    1. Kim D.–H. et al. Epidermal Electronics. Science. 333, 838–843 (2011). - PubMed

Publication types