Electromagnetism has a profound effect on our lives since applications such as wireless and satellite communications, space, airborne or ground active array radars, cable TV, and smart automotive infrastructure all depend on it. All of them are in continuous need of components with improved performance at higher power & frequency, smaller footprint & volume, with increased functionalities and at a lower cost and enhanced reliability. Novel solutions need to be sought to enable the next-generation of products with the efforts focusing on RF front ends (transceivers TRX modules) which are the key electromagnetic component that allows emission and reception of electromagnetic waves. Currently such innovative technologies are GaN based electronic components (high power capacity, low noise, chemically and thermally robust) and RF Microelectromechanical switches (MEMS) (lower insertion loss, higher isolation, greater power handling).
MRG in collaboration with Thales SA (France) has been developing technologies for the monolithic integration of GaN based Monolithic Microwave Integrated Circuits (MMICs) with RF MEMS focusing more on what is termed “coplanar approach”. MRG has already developed GaN based coplanar high power transistors operating in the X-band exhibit performances at par with commercially available “microstrip” ones such as the UMS GH25 transistor. MRG is currently attempting to set up a pilot line for the production of such RF front end modules. 

Starting around 1970, Surface Acoustic Wave (SAW) devices were developed for pulse compression radars, oscillators, and band-pass filters for domestic TV and professional radio applications and recently for mobile or satellite communication systems. The shift of the resonance frequency of a SAW resonator, as effect of change of various physical parameters (temperature, pressure, mass loading, etc.) make these devices very useful in sensing applications. The traditional materials (quartz, langasite, langatate) used in SAW resonators manufacturing have excellent piezoelectric properties but they have also the disadvantage of their limited operating frequency, which remains normally below 2 GHz. Lately, the amount of data transmission in wireless network systems is increasing and the demand for SAW devices operating at frequencies around 5 GHz becomes important. Also in sensor applications, the sensitivity increases with the resonance frequency, being proportional with the square of the resonance frequency for mass, humidity and gas sensors. According to the wave mode there can be waves of Rayleigh, Lamb or a combination of both category. Wide bandgap (WBG) materials like GaN and AlN have very good piezoelectric properties and significantly higher acoustic velocities and are increasingly used for acoustic devices.
For over a decade, MRG has been developing SAWs, Film bulk acoustic resonators (FBARs) mainly for temperature, pressure and humidity sensing, Lamb resonators for biosensing (e.g. protein detection) and UV photodetectors. Key parameters are the developed micromachining process for extremely thin GaN membranes (below 500nm) and the electron beam lithography protocols for extremely narrow and densely packed interdigitated transducers (IDTs) as thin as 100nm with 100nm period.
This activity has resulted in more than 15 publications in established journals with citations in the range of 600 and in numerous conference presentations.

Acoustic sensors: For over a decade, MRG has been developing SAWs, Film bulk acoustic resonators (FBARs) mainly for temperature, pressure and humidity sensing, Lamb resonators for biosensing (e.g. protein detection) and UV photodetectors. Key parameters are the developed micromachining process for extremely thin GaN membranes (below 500nm) and the electron beam lithography protocols for extremely narrow and densely packed interdigitated transducers (IDTs) as thin as 100nm with 100nm period.
EEG sensors: Within the past 5 years, MRG has developed a dry microneedles based  Electroencephalogram (EEG) electrode with simple fabrication involving just a single lithography step without the use of “sacrificial” substrates. The resulting process is therefore simpler and of lower cost.
Gait sensors: MRG as part of a Greek collaborative effort, is working towards the design and manufacture of a smart, wearable insole (Smart Insole) with built-in pressure measurement sensors, other micro-electronic sensing elements and communication devices to tackle the challenge of efficient gait monitoring in real life. This wearable insole is based on unique layer that consists of a polymeric material with embedded piezoelectric flakes, an inertial measurement unit including a triaxial accelerometer, gyroscope and magnetometer to capture the gait characteristics in motion.

Future RF systems are in continuous need of components with improved performance at higher power & frequency, smaller footprint & volume, with increased functionalities and at a lower cost and enhanced reliability. Aggressive miniaturization is the key requirement for future RF Transceiver (TRX) systems. In order to achieve, there is a need to transform current TRX 2D architecture into 3D heterogeneously or sequentially integrated one.

MRG conducts research in III-nitride based MMIC, III-nitride based sensors and RF MEMS and has already demonstrated the monolithic integration of MMICs with RF MEMS.  A major advantage of III-nitride based acoustic sensors is the possibility of monolithic integration with other active and passive circuit elements, enhancing the future development of smart microsystem technological platforms on this material. In particular MRG is working on the idea of “all-in-Gallium Nitride” solution involving MMICs, RF MEMS, multimodal sensors supported by disruptive nanotechnologies such as 1D &2D materials, which will deliver a single transceiver component which will radically transform the current 2D TRX architecture into a 3D System in Package (SiP). 

Transparent and Flexible electronics are part of the Key Enabling Technologies of Nanotechnology, Advanced Materials, Photonics and Micro-Nanoelectronics. Flexible and transparent electronic devices and systems can find applications in the high growth market sectors of healthcare, smart packaging for food and pharmaceutical products security, human-machine interfacing, sensor networks, automotive electronics, the Internet of Things, flexible displays, wearable gadgets and other emerging chip markets.
The activity on flexible and transparent electronics within MRG employs low temperature PVD deposition techniques like rf sputtering and rf magnetron sputtering for fabricating n-type and p-type nanostructured oxides, nitrides and oxynitrides like ITO-N, ZnO-N-Al, Ir, NiO-Al, TaO-N, ZnSnO, CuO, etc, with controllable properties and long term stability, on flexible substrates (PET, glass, etc). By making use of innovative and low-cost fabrication-approach devices, TTFTs, photo-transistors, transparent diodes and transparent PVs are developed.