^a Department of Electrical and Electronic Engineering, School of Engineering, Cardiff University, Cardiff CF24 3AA, UK

^b Tissue Micro-Environment Group, Division of Cancer & Genetics, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK

^c School of Life Sciences, Northwestern Polytechnical University, P.R. China

^d Department of Civil Engineering, School of Engineering, Cardiff University, Cardiff CF24 3AA, UK

^e Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK

^f Department of Neurology, Tianjin 4th Centre Hospital Affiliated to Nankai University, P.R. China

^g Department of Biomedical Engineering, School of Engineering, Duke University, NC 27708-0281, USA

^h Centre for Biosensors, Bioelectronics and Biodevices (C3Bio) and Department of Electronic & Electrical Engineering, University of Bath, Bath BA2 7AY, UK

ⁱ School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, P.R. China

^j Preclinical Studies of Renal Tumours Group, Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK

^k Faculty of Engineering and Environment, Northumbria University, Newcastle Upon Tyne, Newcastle NE1 8ST, UK

^l School of Mechanical Engineering, Tianjin University, P.R. China