Dielectric elastomer actuators (DEAs), which are inherently complaint capacitors, are emerging as pseudo-muscular actuators with a wide range of applications. In order to achieve high stretchability for large DEA actuation, carbon nanotube (CNT) and other 1D materials-based electrodes are used to maintain conductance at large strains. These electrodes are typically fabricated using spray coating or filter transfer method and resemble a perforated electrode under high magnification. Hence, there can be a loss of field and stray capacitance when multiple layers of carbon nanotubes (CNTs)-based electrodes are used. This study investigates the effect of microscopic perforations on the nature of electric fields and on the capacitance of multi-layered CNT-based DEA structures with various dimensions and geometric properties of the electrodes. It has been found that the capacitance decreases with increase in the perforations however its effect is limited for a reasonable coverage. The change in normalized is found to be negligible (∼5%) for an electrode coverage area of over 90%, however, the maximum output work reduces by 18.2%. This analysis is important to develop robust and reliable CNT-based DEA structures, without using excessive CNTs which can lead to increased mechanical stiffness of the electrodes.

Heating coils utilize the concept of resistive heating to convert electrical energy into thermal energy. Uniform heating of the target area is the key performance indicator for heating coil design. Highly uniform distribution of temperature can be achieved by using a dense metal distribution in the area under consideration, however, this increases the cost of production significantly. A low-cost and efficient heating coil should have excellent temperature uniformity while having minimum metal consumption. In this work, space-filling fractal curves, such as Peano curve, Hilbert curve and Moore curve of various orders, have been studied as geometries for heating coils. In order to compare them in an effective way, the area of the geometries has been held constant at 30 mm × 30 mm and a constant power of 2 W has been maintained across all the geometries. Further, the thickness of the metal coils and their widths have been kept constant for all geometries. Finite Element Analysis (FEA) results show Hilbert and Moore curves of order-4, and Peano curve of order-3 outperform the typical double-spiral heater in terms of temperature uniformity and metal coil length.