Chemical Processing of Transducer Materials

Transducer materials are functional materials that convert one form of energy into another. They are essential to technologies such as sensors, actuators and radiofrequency (RF) components. These applications are becoming increasingly critical in the context of modern technological demands, which include:

• the need for materials compatible with MEMS/NEMS and flexible electronics, including those that can be integrated with CMOS technologies and processed on transparent or flexible substrates using printing-based techniques;
• the rise of 5G/6G communications, the Internet of Things (IoT) and wearable devices, all of which require transducers that are high performing, miniaturized and energy efficient;
• growing regulatory pressure to eliminate lead-based materials due to environmental and health concerns, driving demand for lead-free piezoelectrics;
   

Beyond traditional applications, ferroelectrics can also convert different types of energy into chemical energy and serve as catalysts in redox reactions, for example water splitting to produce green hydrogen.

A set of interrelated challenges must be addressed to enable the next generation of transducer technologies:

• Manufacturing scalability – Solution-based approaches such as sol-gel processing, inkjet printing and aerosol-jet printing offer promising routes for low-cost, flexible and material-efficient fabrication, but require further development to meet industry standards;
• Performance trade-offs – Achieving an optimal balance of performance, operational stability, sustainability and processability remains difficult. This can be seen with lead-free materials, which, while more sustainable, often lag behind their lead-based counterparts in performance.
• Novel application areas – The use of transducer materials in mm-wave communications, quantum technologies and catalysis requires research on high-frequency and low-temperature properties, as well as investigations of novel phenomena.

Objectives

The main objective of the Chemical Processing of Transducer Materials is to lead the research and development of transducer materials through innovative chemistry-based processing techniques. With a strong background in ferroelectric materials, the group aims to create scalable and cost-effective solutions for next-generation electronic devices and beyond. It is also committed to fostering doctoral education and advancing knowledge through collaborations with academic and industrial partners.

Scope of expertise

Sensors and actuators

Piezoelectric haptics
Piezoelectric haptic technologies offer high-quality and fast response vibrotactile feedback. Piezoelectric actuators generate ultrasonic vibrations in a plate (such as a screen), enabling real-time control of the friction coefficient between the finger and the surface as the finger moves across it. The group is developing advanced processing techniques, such as inkjet printing and flash lamp annealing, for the efficient integration of oxide thin-film piezoelectrics, including Pb(Zr,Ti)O₃, onto glass substrates. These structures are used in proof-of-concept haptic devices.

Lead-free piezoelectric materials
Lead-based piezoelectrics remain the benchmark for sensing and actuator applications due to their superior performance. However, their toxicity poses significant risks to both human health and the environment. The group is therefore exploring alternative lead-free thin-film piezoelectric materials. Current work focuses on (K,Na)NbO₃, which exhibits a strong piezoelectric response suitable for actuator applications, and on ferroelectric HfO₂ - an unconventional ferroelectric with moderate piezoelectric properties that shows promise for use in resonator devices.
 

Printed temperature and strain sensors
Sensors play a vital role in advancing sustainability and improving quality of life. Unlocking their full potential requires the development of simple, low-cost fabrication technologies. The group focuses on temperature and strain sensors using printed conductive materials. Deposition techniques, such as inkjet and aerosol jet printing, are employed, followed by light-based thermal treatments including laser and flash lamp annealing. These sensors are targeted for use in structural health monitoring across a range of industries, including aerospace.

Electro-optic devices

The electro-optic effect enables modulation of a ferroelectric film’s refractive index by applying an external electric field. This phenomenon is essential for controlling light transmission in optical chips, tunable photonic gratings and photon-based quantum processors.
In addition to conventional linear electro-optic effects, the group investigates extrinsic mechanisms, such as field-induced phase transitions and reversible ferroelectric domain switching, that produce significantly stronger responses. These enhanced effects open up opportunities for the further miniaturization of optics-based devices.
 

5G & 6G materials

In response to the growing demand for high-frequency electromagnetic devices operating in the millimetre-wave range and beyond, and driven by applications such as 5G/6G communications and remote sensing (e.g. automotive radar for autonomous vehicles), the group focuses on two key areas:

(1) printing  conductive materials, including transparent indium tin oxide (ITO) and various metals, for antenna fabrication; 
(2) developing ferroelectric substrates with ultra-high, electrically tuneable dielectric permittivity, such as Pb(Zr,Ti)O₃ on glass. The overarching goals are to enable seamless integration of antennas into a wide range of objects, and to further miniaturize devices, thereby enhancing their functionality.