Figure 1

Structure, characteristics, and fabrication procedure of the silicone-based stretchable fiber pumps. (a) Use of silicone elastomer enables high flexibility and stretchability in the pumps. (b) Pumps consist of a pair of conductive wires as electrodes, embedded in a silicone tube. The electrodes are coiled in a parallel helical form. (c) Working principle of the pumps. Dielectric fluid molecules are ionized by electric fields generated between the electrodes produced by application of high voltage. The ionized molecules are accelerated by the electric fields, thereby creating one directional flow. (d) The fiber pumps are highly stretchable, allowing 40% strain. (e) The distance between conductive wires, designated as \({d}_{0}\) (1 mm), is increased when the pump is stretched (\({d>d}_{0}\)). At the time, the capacitance between the electrodes, represented as \({C}_{0}\) decreases (\({C<C}_{0}\)). (f) The capacitance change can be exploited to use the pumps as a capacitive strain sensor. (g) Fabrication process of the pumps. (i) Conductive wires are coiled around a brass rod. (ii, iii) The rod is then dipped into a silicone mixture. (iv) The rod covered with the silicone mixture is cured in an oven. (v, vi) The rod is inverted and dipped again. (vii) The rod with the silicone mixture is again cured in the oven. Steps (ii) through (vii) are repeated four times in total. (viii) After curing the silicone, the brass rod is then extracted, leaving a silicone tube. (ix) Connectors are inserted into both ends of the silicone tube.