1. School of Material Science and Technology, Guangdong University of Petrochemical Technology, Maoming, China
2. Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
3. School of Chemistry and Materials Engineering, Huizhou University, Huizhou, China
4. Centre for Medical and Industrial Ultrasonics, James Watt School of Engineering, University of Glasgow, Glasgow, UK