UC San Diego

Soft robotics is a promising field that can solve several limitations of traditional rigid robotics. These systems are composed of soft and flexible materials to achieve high degrees-of-freedom and compliance with their surroundings. An important part of soft robotics is developing methods to actuate the soft structures. A popular method involves inflating soft hollow structures with a pneumatic pump that can achieve rapid and precise actuation. However, the structure must be tethered to a heavy and rigid pump, which limits its application. An alternative method vaporizes embedded liquid to inflate the structure instead. The simplest and widely used design to vaporize such liquid is by installing a heating element near the liquid. Heating the system beyond the boiling point rapidly boils the liquid and deforms the structure. The small amount of liquid and heater makes it easier to be packaged into a portable device. Nevertheless, this technique possesses several limitations that must be improved to be practical. This dissertation addresses these limitations and introduces methods that can advance the field for future robotics. Chapter 2 describes how actuation through vaporization can be affected by the environment and introduces a system that consists of double-layered walls and a thermoelectric device. Chapter 3 aims to implement ultrasonic waves that propagate through materials, which enables a system with detachable parts. Chapter 4 utilizes vibrating mesh atomization to drastically improve the slow actuation speed by evaporating small droplets with large surface areas. Last, chapter 5 introduces a method that can potentially remove electrical components by combining ultrasonics with shape optimization. These studies show that soft actuation through vaporization has significant room for improvement and can potentially replace commercial actuation methods with further optimization.