From 1987, the year in which Dr. Arnau Mir finished his degree, until 1994, he was working in the group of dynamic systems at the University of Barcelona. The result of this work was his doctoral thesis. From 1995 to 2006, he was collaborating on the one hand with Professor Pedro Salvador, CSIC research professor in the analysis of photoelectrochemical images for the characterization of semiconductors and on the other hand he was part of the Graphics and Vision group of the Universitat de les Illes Balears and worked on the deformation and simulation of objects. The result of this work was the co-supervision of two doctoral theses with the qualification of Excellent Cum Laude.

As of 2006, he joined the Bioinformatics group of the University of the Balearic Islands, working on the one hand on the balance indices of rooted and unrooted binary trees, studying statistical properties of these balance indices under the evolution models of Yule, uniform and the Ford's model alpha-gamma. All this work led to the co-direction of a doctoral thesis on balance indexes with an Excellent Cum Laude rating that was read this July 2020.

He is also a collaborator in the Soft Computing and Image Processing and Aggregation research group (SCOPIA). His work focuses on contour detection and image denoising (particularly medical imaging) using fuzzy techniques.
He is the author of more than 30 articles in Q1 and Q2 journals in his research area and more than 50 papers in conference proceedings and book chapters.