Nanotechnology has been around for a while. There have been lots of promises resulting in a few solid applications, a number of promising medical advances, and a number of possibilities, which are still in the research stage. What is often overlooked is the advances made in science to be able to evaluate the new materials. Microscopy has advanced to the point where pictures of bonding between atoms can be recorded. Modeling capabilities have improved to the point where some material properties can be predicted. There is the ability to layer 2-D sheets of materials to create desired properties. It is possible to determine substitute materials for applications that have a requirement to not employ certain chemicals or materials. As researchers learn more about the properties of material, they are able to develop new materials to solve existing problems that have arisen due to existing material hardness or toxicity of materials currently required. Below are two examples of work being done that demonstrate the above statement.
Research at IIT Bombay [Ref. 1] has been focused on changing the material in Piezoelectric Nanogenerators (PENGs) in order to be able to incorporate energy harvesting devices into the human body. The detractor has been the need to use highly toxic ceramics, of which lead zirconate titanate (PZT) is a primary example. The researchers worked with a hybrid perovskites that should not have had the ability to produce spontaneous polarization. (Perovskite refers to any material that has the same type crystal structure as calcium titanium oxide. Perovskites have had a major impact on the solar industry in the last few years.) This work demonstrated a far greater piezoelectric response than the best non-toxic material, BaTiO3.
After the original results, the researchers considered enhancements of incorporating the material into a ferroelectric polymer. The results were surprising in that they doubled the power over their original material. They have achieved a production of one volt for a crystal lattice contraction of 73 picometers. There is much work yet to be done, but there is a long list of possible medical applications that could apply this material.
Work performed at Zi’an Jiaotong University is based on a soft dielectric material that creates voltage when bent [Ref. 2]. When certain materials are non-uniformly deformed, the strain gradient creates a separation of positive and negative ions, which develops a voltage across the material. This action can be observed in many different dielectric materials. Unfortunately, this effect is strongest in brittle ceramic materials. The brittleness property makes the materials unsuitable for applications, like stretchable electronics. The researchers have developed a process to add a layer of permanent negative charges within certain materials. The material at rest, no stress, has no voltage between the top and bottom of the material. If a bar of the material is clamped on both ends and the middle of the bar subject to a deforming process, high voltages can be developed. The researchers reported measuring -5,723 Volts.
The idea is that with new tools and the resulting knowledge obtained, it is possible to look at applications that are needed that currently require materials that are not suitable for the environment of the applications. In many cases this environment is inside the human body.