Beatriz Noheda & Guus Rijnders (U Twente) receive TOP-PUNT grant for "Searching for the 'Silicon' of Piezoelectrics: Morphotrophic Quartz"

ZIAM researcher Beatriz Noheda and her colleague Guus Rijnders from MESA+ (U Twente) receive a TOP-PUNT grant worth 1.75 MEuro for exploring novel, lead-free piezoelectrics based on Silicon. Their research will pave the way for self-powered medical implants like pacemakers or sensors.

The science behind the grant

Piezoelectrics are materials that can transform mechanical energy into electrical energy and vice versa. This is thanks to their ability to deform under an electric field and, conversely, to produce an electric field when deformed. Because of this unique property, they are the active elements of many everyday applications, from ink-jet printers to ultrasound generators, representing a billion euro industry.

Undoubtedly, piezoelectrics are an important part of modern technology: hospitals use piezoelectrics in ultrasound generators for echography scanners, lithotripters to break kidney stones, ultrasound cleaners or inhalators; the automotive industry uses piezoelectrics in shock detectors within airbags, in mirror positioners, ABS systems, accelerometers, diesel injection valves, fuel level meters, tire pressure sensors, parking aid systems, vibration dampers and several others. But piezoelectrics can offer much more. In particular, they could play an important role in low-power energy harvesting, allowing autonomous powering of small electronics, by converting ubiquitous vibrations (wasted mechanical energy), into electricity. Self-powering of sensors would greatly help the development of concepts like the Internet of Things. Piezoelectrics are also being considered for self-powered pacemakers, drug delivery systems or sensors of blood pressure or of sugar levels to be placed inside the human body.

In order to enable these and other future applications, two main developments are eagerly awaited in the field:
1) miniaturization, for energy efficiency and integration in electronics. For this, further enhancement of the materials responses is required in order to maintain their functionality at the nanometer scale;
2) discovery of non-toxic and abundant piezoelectrics with comparable properties (including temperature stability) as those of the current, lead-based, compounds.

Recently, our understanding of the mechanisms leading to large piezoelectricity, as well as the synthesis techniques, have improved to such extent that these objectives are finally feasible. The goal of this proposal is to synthesize new materials with large piezoelectric responses in thin film form, made of harmless and widely available elements. More specifically, we will venture into Si-based piezoelectrics. The key idea is to go back to Nature, that already delivers such materials: quartz crystals, containing the same harmless and abundant elements of silica (SiO₂), of which our Earth’s crust is full. The project will implement different strategies to improve the piezoelectric response of quartz such that its performance for energy harvesting applications becomes comparable to that of current lead-containing compounds.

NWO Press release (Dutch)