"Self-folding of polymer sheets using local light absorption". Y: Liu, J. K. Boyles, J. Genzer, M. D. Dickey. Soft Matter. IN PRESS. doi: 10.1039/c1sm06564e
This paper demonstrates experimentally and models computationally a novel and simple approach for
self-folding of thin sheets of polymer using unfocused light. The sheets are made of optically
transparent, pre-strained polystyrene (also known as Shrinky-Dinks) that shrink in-plane if heated
uniformly. Black ink patterned on either side of the polymer sheet provides localized absorption of
light, which heats the underlying polymer to temperatures above its glass transition. At these
temperatures, the predefined inked regions (i.e., hinges) relax and shrink, and thereby cause the planar
sheet to fold into a three-dimensional object. Self-folding is therefore achieved in a simple manner
without the use of multiple fabrication steps and converts a uniform external stimulus (i.e., unfocused
light) on an otherwise compositionally homogenous substrate into a hinging response. Modeling
captures effectively the experimental folding trends as a function of the hinge width and support
temperature and suggests that the hinged region must exceed the glass transition temperature of the
sheet for folding to occur.
self-folding of thin sheets of polymer using unfocused light. The sheets are made of optically
transparent, pre-strained polystyrene (also known as Shrinky-Dinks) that shrink in-plane if heated
uniformly. Black ink patterned on either side of the polymer sheet provides localized absorption of
light, which heats the underlying polymer to temperatures above its glass transition. At these
temperatures, the predefined inked regions (i.e., hinges) relax and shrink, and thereby cause the planar
sheet to fold into a three-dimensional object. Self-folding is therefore achieved in a simple manner
without the use of multiple fabrication steps and converts a uniform external stimulus (i.e., unfocused
light) on an otherwise compositionally homogenous substrate into a hinging response. Modeling
captures effectively the experimental folding trends as a function of the hinge width and support
temperature and suggests that the hinged region must exceed the glass transition temperature of the
sheet for folding to occur.
Este trabajo demuestra experimentalmente y mediante modelos computacionales una manera sencilla y nueva para el autodoblado de láminas de polímeros mediante luz no focalizada. Las láminas están hechas de poliestireno transparente tensado previamente (también conocido como "Shrinky-Dinks"), que se enconge en un plano si se calienta uniformemente. A partir de patrones hechos con tinta negra en cada lado de la lámina de polímeros se logra la absorción localizada de luz, la cual calienta al polímero subyacente a temperaturas superiores a la de su transición vítrea. A estas temperaturas, la regiones preestablecidas por la tinta (i.e. bisagras) se relajan y encogen, y así provoca que la lámina plana se doble formando un objeto tridimensional. Es así como el autodoblado se consigue de manera sencilla sin necesidad de múltiples pasos de fabricación y transforma un estímulo externo uniforme (i.e. luz no focalizada) en una respuesta de bisagras, que de otra manera se mantendría como un substrato homogéneo. La modelación contiene efectivamente las características del doblado experimental como función del ancho de las bisagras y de la temperatura de soporte y sugiere que la región que funciona como bisagra debe exceder la temperatura de transición vítrea de la lámina para que ocurra el doblado.
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