Design of compliant valves that can be integrated into a fluidic network

Abstract

Building a distributed fluidic actuation system is a challenge due to every actuator needs its own control valve. Due to this, an n by an array of actuators needs n 2 number of valves. A logic network of valves provides a solution by reducing the number of valves needed to operate such distributed fluidic actuation system. These compliant fluidic networks could have a broad application in different fields such as biomedical, microfluidics, or in soft robotics. An example in the biomedical field is for creating an actuated surface that is controlled by a fluidic logic that goes around a hollow organ. This sleeve could provide support to the organ by externally providing actuation. The main goal of the paper is to design a compliant valve that easily could be integrated into a large fluidic logic network, to demonstrate the network a demultiplexer is built. Compliant is defined as soft material (small E modules) with hyperplastic properties. To get a better understanding of what is already done in the field of distributed actuation systems a literature study is conducted. The thesis will provide information on the design steps of creating a valve and how to integrate them in a fluidic network that is a demultiplexer. The operating principle of this valve is that there are 2 channels on top of each other on a 90-degree angle, one channel will be inflated and will choke the other channel. Different valve designs based on this principle have been built and tested using different shapes and combinations of materials. Using FEM software the closing pressure is calculated. After that prototypes have been built and experiments are conducted. During experiments, the pressure drop has been measured in the channel that will be closed. The next step is to understand how these valves operate in a large network. A Simulink model of a demultiplexer has been built, it was shown that 2.4 seconds to inflate an array of 8 small bellow actuators with a stroke of 5 mm. After simulating a demultiplexer is created. Experimental results show that the best-performing valve completely closes a line with a pressure of 12 kPa with an operating pressure of 26 kPa. As a demonstrator of a large-scale network a demultiplexer is built, unfortunately, it did not perform due to manufacturing problems. To answer the main question of this paper a fully functioning logic network has not yet been achieved however, it could be said that this paper has laid a good foundation for further improvement of the creation of a scalable solution for an actuating surface. It also has to be noted that the valve designs that are discussed in this paper operate on an mm scale instead of an cm-scale which is commonly found in the literature.