Barely noticed by the general public, piezoelectricity has become an innovation motor, which worldwide has initiated new markets with turnover of billions of dollars. The piezoelectric market covers a very wide range of technical applications; it is especially strong in the fields of information and communications, industrial automation, medical diagnostics, automation and traffic control, and in the defense industries.

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  Layers in Piezo Roads

All these innovations are materials based. Thus, on the one hand, the story of piezoelectric innovations cannot be understood as a simple market pull process. On the other hand, a simple science fiction of its inception with statements like “the recently invented class of piezoelectric substances offers many novel possibilities and by exploiting these opportunities an avalanche of novel products will develop changing our lives” does not hold either. Materials-based innovations are usually far more complex. There is mutual stimulation between advances in materials and processing technologies, on the one hand, and technical and economic requirements of new and improved applications on the other, i.e., both market pull and technology push are important inter-correlated factors.

Similarly, the way piezoelectricity entered substantially into the market place was most unusual. Piezoelectricity was first discovered by the Curie brothers in 1880, but no until one century later did we realize the current avalanche of products developing in this market. Interesting questions are what happened during the period of long delay on one hand, and what catalyzed the present avalanche of progress on the other.From the perspective of solid-state physics, crystalline materials that become electrically polarized when subjected to mechanical stress and conversely change shape when under an applied electric field, namely piezoelectrics, certainly merit study. Technologically, however, the phenomenon only becomes interesting to the broader engineering community when it offers an effect large enough to usefully convert electrical power or signals into mechanical ones or vice-versa. This is the first essential condition, and there are also always a lot of additional needs like small conversion losses, temperature and long time stability, reproducibility, reliability, cost and other market needs.

Out of the family of such requirement for a given device, and the measured material properties, a figure of merit can be formulated. Now we have to compare these figures of merit with the corresponding ones for already existing systems in current applications.

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  Design : PiezoPads by Fujitsu

From general experience, it is known that a new novel technology will not succeed in application unless it offers at least a factor of three advantages. Otherwise, in the inertia born tendency for existing solutions to survive, the current approach will be improved by a factor of this order as soon as it is perceived to be endangered. To effectively enter the market piezoelectrics always had to compete with well-known electromagnetic devices, as for example relays and electromagnetic motors. Only in the case of substantial advantage would they be accepted technically or commercially. Clearly this competition was the major reason for the above-mentioned long delay of the technical break-through to large scale applications.

Summarizing, concerning the multitude of piezoelectric materials and device applications existing already, today we may expect continuous futuredevelopment and fascinating new novel application areas. Above all we canexpect transfer of macrosystems into the micro and nano worlds, the search for lead free and environmentally more friendly highly active piezoelectrics will continue, and last but not least the piezoelectric effect in well textured or even single crystalline Pb(ZrTi)O3 like systems could surmount the already known strong piezo effects by an order of magnitude enlarging once more the already very broad current field of applications.