Analyzing the Strain Sensing Response of Photoactive Thin Films Using Absorption Spectroscopy


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Structural health monitoring systems are required for detecting damage in structures so as to facilitate their timely maintenance and repair and to prevent catastrophic structural failure. To date, a variety of different sensor platforms (e.g., piezoelectric materials, fiber optics, and wireless sensors) have been proposed for SHM. However, they still suffer from high energy demand, large form factors, and durability issues, particularly when applied for monitoring space structures and reusable spacecraft. In a previous study, a bio-inspired and photocurrent-based strain sensor has been developed. This poly(3-hexylthiophene) (P3HT)-based nanocomposite sensor has been shown to generate photocurrent whose magnitude varies in tandem with applied strain. However, the photocurrent generation performance of the sensor is quite low. In addition, the strain sensing mechanism is not fully understood. In this study, the performance of the photoactive thin films were enhanced, and its strain sensing characteristics were analyzed using ultraviolet-visible (UV-Vis) absorption spectroscopy. First, multilayered photoactive and P3HT-based thin films were assembled via spin coating. The photocurrent generation performance of the films was evaluated using two methodologies, namely its photocurrent time history and current-voltage (IV) response. Uniform coating of the photoactive layer and high purity aluminum electrodes were crucial for improving their photocurrent generation. Second, light absorption properties of the P3HT-based photoactive layer were investigated at different strain levels using a UV-Vis spectrophotometer. Light absorption was shown to vary linearly with applied tensile strains.



Key Engineering Materials (Volumes 569-570)

Edited by:

Biswajit Basu




D. H. Ryu and K. J. Loh, "Analyzing the Strain Sensing Response of Photoactive Thin Films Using Absorption Spectroscopy", Key Engineering Materials, Vols. 569-570, pp. 695-701, 2013

Online since:

July 2013




[1] E. Wolfgang, L. Ines, W. Reinhardt, R. Arnd, and G. Roland, Fibre optic sensor network for spacecraft health monitoring, Meas. Sci. Technol. 12 7 (2001) 974-980.

[2] V. Giurgiutiu, A. Zagrai, and J.J. Bao, Piezoelectric wafer embedded active sensors for aging aircraft structural health monitoring, Struct. Health Monit. 1 1 (2002) 41-61.


[3] J.L. Jaques, D.E. Adams, D. Doyle, and W. Reynolds, Experimental study of impact modulation for quantifying loose bolt torque in on-demand satellites, ASME Conf. Proc. (2010) 727-734.


[4] E.W. Taylor, Inorganic and polymer photonic sensor technologies in space missions, IEEE Conf. Proc. (2001) 2006-(2013).

[5] A.D. Kersey, M.A. Davis, H.J. Patrick, M. Leblanc, K.P. Koo, C.G. Askins, M.A. Putnam, and E.J. Friebele, Fiber grating sensors, J. Lightwave Technol. 15 8 (1997) 1442-1463.


[6] G.C. Kahandawa, J. Epaarachchi, H. Wang, and K.T. Lau, Use of FBG sensors for SHM in aerospace structures, Photonic Sensors 2 3 (2012) 203-214.


[7] A. Zagrai, D. Doyle, V. Gigineishvili, J. Brown, H. Gardenier, and B. Arritt, Piezoelectric wafer active sensor structural health monitoring of space structures, J. of Intell. Mater. Syst. and Struct. 21 9 (2010) 921-940.


[8] D. Ryu and K.J. Loh, Strain sensing using photocurrent generated by photoactive P3HT-based nanocomposites, Smart Mater. Struct. 21 6 (2012) 065016.


[9] D. Ryu and K.J. Loh, Self-sensing photoactive thin films for monitoring space structures, ASME Conf. Proc. (2012) 1-8.

[10] S. Günes, H. Neugebauer, and N. S. Sariciftci, Conjugated polymer-based organic solar cells, Chem. Rev. 107 4 (2007) 1324-1338.


[11] L. Li, G. Lu, and X. Yang, Improving performance of polymer photovoltaic devices using an annealing-free approach via construction of ordered aggregates in solution, J. Mater. Chem. 18 17 (2008) 1984-(1990).


[12] D. Chirvase, J. Parisi, J. C. Hummelen, and V. Dyakonov, Influence of nanomorphology on the photovoltaic action of polymer–fullerene composites, Nanotechnology 15 9 (2004) 1317-1323.


[13] J. Roncali, Conjugated poly(thiophenes): synthesis, functionalization, and applications, Chem. Rev. 92 4 (1992) 711-738.


[14] T.A. Skotheim, R.L. Elsenbaumer, and J.R. Reynolds, Handbook of conducting polymers, second ed., Dekker, New York, (1998).