ProfessorNorbert Klein

summary of Research activities of the “Electromagnetic Materials and Sensor” group
We focus both on science and technology of nanomaterials, our current goal is to develop and realize novel sensor concepts based on nanomaterials, functional materials and heterostructures made from both. We are targeting label-free sensing of biological species and early state disease indicators, such as exosomes and circulating tumour cells, but also gas sensors for environmental monitoring. We are combining novel device concepts based on nanomaterials with electromagnetic sensor operation modes, such as microwave impedance, surface acoustic waves and infrared and terahertz plasmons. According to my experience with a successful spin-off for liquid explosive detection in airports (www.emisens.com) our research is aiming towards the practical use of sensors for real-world applications.Below a list of current research projects where we are looking for PhD and Master students. As part of their training, the students will have access to the thin film technology lab () and learn how to use thin film deposition and device microfabrication methods in a cleanroom environment, in addition to access to modern microscopy facilities () as well as they will receive training in advanced electromagnetic characterization methods such as microwave S-parameter measurements and Raman spectroscopy.

TOPIC 1: Nanomaterials growth and characterization


Fig. 1: Quasioptical system for graphene characterization at millimetre wave frequencies

The growth of wafer scale graphene using state-of-art chemical vapor deposition technique, large area transfer, characterization and understanding of the fundamental properties of these materials is part of the group focus. We use Raman, XPS, Kelvin Probe Microscopy, and electromagnetic characterization from DC to terahertz frequencies for characterization of graphene. In addition, we develop a novel device concepts based on 2D materials and integrate them into electronic sensors for environmental and real time detection of diseases. Another focus of the group is the synthesis of high quality 2D materials directly onto substrates, which would be an important step for the materials to be implemented in practical applications.

topic 2: Graphene dual mode biosensors for exosome and cell detection


Fig. 2: Exosome detection based on the electric field effect in graphene (top) and technical realization of a graphene biosensor array with integrated microfluidic channel (bottom).

We are combining charge detection via the electric field effect in graphene with mass detection using surface acoustic wave (SAW) radio frequency devices. The combination of two complementary readout schemes in one device enables separation of target exosomes from other non-specific immobilized species, aiming to improve accuracy of early-state cancer diagnostics.topic 3: Graphene - aluminium nitride heterostructures for micro-acoustic sensor devices

Fig. 3: CVD graphene deposition system for 4 inch wafers (top) and microwave cavity measurement system for graphene-aluminium nitride – graphene multilayers (bottom).

Due to the piezoelectric properties and low losses of aluminium nitride (AlN), micro-acoustic devices based on AlN thin films are used as sensors and frequency selective components in modern wireless communication systems. The combination with graphene as metal electrodes enables ultrasensitive mass and charge detection within one device, with potential use as gas sensors with enhanced chemical selectivity.

Our team and our partners
Professional researchers: Dr Sami Ramadan, Dr Olena Shaforost, Dr Clare Watts

PhD students: Mr Yuanzhou Zhang, Ms Deana Kwong Hong Tsang

Visiting scientists: Dr Stephen Hanham (University of Birmingham), Dr Ling Hao (National Physical Laboratory)

Collaborators within Imperial College: Dr Iain Dunlop (Materials), Dr Peter Petrov (Materials), Dr Johannes Lischner (Materials), Dr Armando del Rui Hernandez (Bioengineering), Prof Jiao Long (Medicine), Prof Sir John Pendry (Physics)

External Academic Collaborators: Dr Stephen Hanham (University of Birmingham), Dr Ling Hao, Dr John Gallop, Dr Nicola Black (National Physical Laboratory), Prof Dagmar Gerthsen (KIT Germany), Dr Hagen Schmidt (IFW Dresden, Germany); Prof Sir Colin Humphreys (Queen Mary University of London); Dr Anna Regoutz (University College London); Dr Chen Fu (Schenzhen University, China)

Industry Collaborations:

Paragraf (www.paragraf.com);

Link Microtek (www.linkmicrotek.com)

EMISENS (www.emisens.com )

ENTIA (www.entia.co)

LG Electronics (www.lg.com)

topic 4: Microwave detection of single cells for liquid biopsies
Single Cell detection by a microwave resonator
Video: Real-time microwave dielectric measurement of polystyrene microparticles flowing inside a microfluidic channel.

The analysis of single flowing cells in a lab-on chip device represents a promising tool for early state cancer diagnostics (circulating tumour cell detection), but also a non-invasive tool to monitor the progression of diseases (liquid biopsy of urine samples). Our unique “microfluidic microwave cavity sensor” enables cell size and cell water content measurements – both know to be physiological tumour cell markers. We are planning to combine microwave single cell measurements with acoustic cell sorting, aiming to develop lab-on-chip devices can be used for liquid biopsies.