Origami MEMS
227
an external force. Molecular dynamics simulations show that the folding of graphene
using a droplet of liquid is possible too.
A solvent exchange folding is possible with graphene. Graphene-based paper
can be designed in such a way that it folds when absorbs water [113]. Fabrication
of such a material is performed by locally converting graphene oxide (GO) to GO
with polydopamine. When reduced, GO is converted into reduced GO (rGO) that
are hydrophobic whereas GO-poly dopamine remains hydrophilic. This difference
in the affinity of both materials toward water leads to the local absorption of water
to induce reversible bending.
(2) By integrating carbon onto other materials
Graphene grown by chemical vapor deposition can be transferred onto SU8 by taking
advantage of the adhesion force between them [30]. Polyhedral shapes containing
graphene are fabricated by combining this transfer with the self-folding of differentially cross-linked SU8 that was explained earlier. This technique offers a new
pathway to exploit the attractive qualities of the graphene more effectively. Earlier,
we also mentioned about SiO 2 -based bimorphs that fold due to residual stress. By
including graphene also into that bimorph, a graphene origami can be developed
[109].
(3) By converting folded polymer shape to carbon
Polymers with carbon-rich backbones can be converted into carbon through heat
treatment in an inert environment (pyrolysis). During the process, molecules other
than carbon are removed, leaving the carbon behind. Interestingly, such a conversion
into carbon retains the original polymer shape, but isometrically shrunken. Cellulosic
paper survives pyrolysis. So does any forms that are made using cellulosic paper [60].
Therefore, structures made of carbon can be realized by pyrolyzing the paper-based
origami. SU8-based polyhedral shapes that are made using capillary origami also
can be converted into the corresponding carbon shapes through pyrolysis.
6 Applications of Origami MEMS
Origami at a smaller length scale has various applications in fields including optics,
electronics, and biology. The major applications are listed in Table 3.
7 Conclusion
In this chapter, we discussed various strategies for microfabricating origami.
Different tactics are generalized as bimorph approach, gradient approach, and
227
an external force. Molecular dynamics simulations show that the folding of graphene
using a droplet of liquid is possible too.
A solvent exchange folding is possible with graphene. Graphene-based paper
can be designed in such a way that it folds when absorbs water [113]. Fabrication
of such a material is performed by locally converting graphene oxide (GO) to GO
with polydopamine. When reduced, GO is converted into reduced GO (rGO) that
are hydrophobic whereas GO-poly dopamine remains hydrophilic. This difference
in the affinity of both materials toward water leads to the local absorption of water
to induce reversible bending.
(2) By integrating carbon onto other materials
Graphene grown by chemical vapor deposition can be transferred onto SU8 by taking
advantage of the adhesion force between them [30]. Polyhedral shapes containing
graphene are fabricated by combining this transfer with the self-folding of differentially cross-linked SU8 that was explained earlier. This technique offers a new
pathway to exploit the attractive qualities of the graphene more effectively. Earlier,
we also mentioned about SiO 2 -based bimorphs that fold due to residual stress. By
including graphene also into that bimorph, a graphene origami can be developed
[109].
(3) By converting folded polymer shape to carbon
Polymers with carbon-rich backbones can be converted into carbon through heat
treatment in an inert environment (pyrolysis). During the process, molecules other
than carbon are removed, leaving the carbon behind. Interestingly, such a conversion
into carbon retains the original polymer shape, but isometrically shrunken. Cellulosic
paper survives pyrolysis. So does any forms that are made using cellulosic paper [60].
Therefore, structures made of carbon can be realized by pyrolyzing the paper-based
origami. SU8-based polyhedral shapes that are made using capillary origami also
can be converted into the corresponding carbon shapes through pyrolysis.
6 Applications of Origami MEMS
Origami at a smaller length scale has various applications in fields including optics,
electronics, and biology. The major applications are listed in Table 3.
7 Conclusion
In this chapter, we discussed various strategies for microfabricating origami.
Different tactics are generalized as bimorph approach, gradient approach, and