Abstract
Mechano-acoustic signals provide users a plethora of information related to the body conditions. When acoustic vibration of certain low frequencies and amplitude is applied directly onto specific body areas, it not only enables hearing, but also brings benefits such as increased blood flow and can be used in physical therapies. Here we look at spin coating and direct ink writing (DIW) as a low-cost and quick fabrication method to fabricate thin-film microchannel devices. We determine the parameters to successfully print the self-supporting hollow microchannels using silicon and a 27 G nozzle to be (1) height from print bed < 0.25 mm, (2) print speed = 7.5 mm/s, and (3) cover pitch < 0.2 mm. Liquid metal Galinstan is injected into the cured microchannels to create the conductive tracks. The combination of the two materials, silicon and Galinstan, ensures the microchannels’ stretchability, flexibility, and conformability to the skin’s surface. We show the fabrication of a functional bone-conduction speaker that is capable of equally distributing sound energies across a sine sweep of 100 Hz to 10,000 Hz. This makes the microchannel film speaker suitable for audio and speech uses. We also show its ability to output acoustic frequencies on two biological samples, (1) porcine skin and (2) chicken skin. Lastly, we also present the versatility of the spin coating with DIW method to fabricate an ingestible and digestible film circuit board. Our circuit film is made of two main materials: (1) Gelatin and (2) Vegemite and its ability to create a full electrical connection to light up an LED is shown in this thesis.