Figure 5: On-demand fluorescent patterns formed by EMCR elastomers under electric fields.

(a) Optical microscope image, (b) fluorescent microscope image and (c) calculated first invariant in the EMCR film with aligned crater patterns under applied field of 68.5 kV mm⁻¹ (applied voltage is 15 kV). The inset in a illustrates the stress state of the pre-stretched EMCR film under an electric field. The inset in b shows the fluorescence intensity along a semi-circumference path of a fluorescent ring (indicated as a cured arrow). The inset of c shows the calculated first invariant along the path. (d) Optical microscope image, (e) fluorescent microscope image and (f) calculated first invariant of trenches formed in the pre-stretched EMCR film under applied field of 59.1 kV mm⁻¹ (applied voltage is 12.8 kV). The insets of e and f show the fluorescence intensity and calculated first invariant along indicated paths, respectively. In a,b,d and e, the thicknesses of EMCR elastomer and buffer elastomer are ~21 and ~106 μm, respectively. (g) Optical microscope image, (h) fluorescent image and (i) calculated first invariant of a ‘U’ pattern in the EMCR film bonded on a buffer substrate embedded with a rigid object. The inset in g illustrates the mechanism of the pattern formation. The insets of h and i show the fluorescence intensity and calculated first invariant along indicated paths, respectively. In g and h, the thicknesses of EMCR elastomer and buffer elastomer are ~21 and ~100 μm, respectively; the applied voltage is 17 kV. The scale bars in a,b,d,e, g and h denote 250 μm.