Haijun Liu received the B.S. degree in mechanical engineering and the M.S. degree in materials science from Tsinghua University, Beijing, China, in 2002 and 2005, respectively, and the Ph.D. degree in mechanical engineering from the University of Maryland, College Park, MD, USA, in 2012. He is currently a Research Associate with the Department of Mechanical Engineering, University of Maryland and a Guest Researcher with the Sensor Science Division of the National Institute of Standards and Technology, Gaithersburg, MD, USA. His current research interests include bio-inspired acoustic sensors, dynamic pressure measurement in shock wave, acoustic metamaterial, and micro/nano systems in general. He was a future Faculty Fellow from the A. James Clark School of Engineering of the University of Maryland in 2009. He has a U.S. patent on Biology-inspired miniature system and method for sensing and localizing acoustic signals.