PMC

Replica molding of silicone/PDMS using wet paper molds. (a) Images showing the paper mold shapes on a transparent hydrophobic transparency paper, cut using a digital vinyl cutter. The second image shows the wet molds resulting from pipetting of appropriate amount of water followed by capillary suction from the porous paper. The scale bar for both images is 5 mm. (b) Conceptual schematic showing the liquid-assisted molding process. When a dry paper is used as a master mold, polymer premix enters its pores causing the mold to stuck on its surface. On the other hand, after wetting the paper, water infiltrates all the pores of the porous paper matrix. Since water is immiscible with silicones, addition of water facilitates an easier peeling off when the polymer is cured.

Fabrication workflow of the wet paper molding process. The mold fabrication only requires a cellulose paper sheet, an acetate sheet and a vinyl cutter. A sticky paper is laid on an acetate sheet (i) and a digital vinyl cutter is used to cut the mold shapes (ii). After carefully peeling off the background (iii), the dry molds are inspected for desired cutting operation (iv). Measured aliquots of water are pipetted on the molds and allowed to wet the paper through capillary action (v). Polymer mix is added on top (vi) and after curing, the chips is pulled from the mold (vii). The scale bars represent 1.5 cm for (i–iii) and 5 mm for (iv–vii).

Stimuli for functional localizer runs. An example of an intact stimulus used for testing action selectivity is shown in (a). Four frames of the video of the paper cutter are depicted with the sound waveform of the paper cutter. The white diamond symbols represent the time points when the video frames were extracted. A scrambled version of the paper cutter is shown in (b). Two examples of intact visual objects used to test for visuohaptic object selectivity are shown in (c). Two examples of visual textures are shown in (d). Haptic stimuli are not shown, but are described in the methods.

Schematic of the approaches to prepare two different types of Parafilm paper and channels for flow control. In the upper half of the figure, the l-paper was patterned via ablation by scanning a laser spot over the paper surface. In the lower half of the figure, a paper cut-out was inserted into a hollow area in i-paper cut to an identical shape with the laser cutter, and then bonded at the boundary, similar to the principle of a jigsaw puzzle.