Abstract
An acetone sensor device comprises: an air containing chamber for containing an exhaled sample of a participant; and an acetone sensing element provided in the air containing chamber for generating an output current based on the acetone concentration of the exhaled sample. The acetone sensing element comprises: a substrate; a buffer layer deposited on the substrate; an InN epitaxial layer deposited on the buffer layer for providing a current path for the output current; a first conductive contact deposited on the InN epitaxial layer for providing a drain contact; and a second conductive contact deposited on the InN epitaxial layer for providing a source contact.