Researchers have created electrostatic materials that function even with extremely weak ultrasound, heralding the era of permanent implantable electronic devices in biomedicine. Recent research explores implantable medical devices that operate wirelessly, yet finding a safe energy source and protective materials remains challenging. Presently, titanium (Ti) is used due to its biocompatibility and durability. However, radio waves cannot pass through this metal, necessitating a separate antenna for wireless power transmission. Consequently, this enlarges the device size, creating more discomfort for patients.

The research team developed an electrostatic material capable of responding to weak ultrasound by utilizing a composite of high dielectric1 polymers (P(VDF-TrFE)) and a high dielectric constant ceramic material known as calcium copper titanate (CCTO, CaCu3Ti4O12). This material generates static electricity through friction between its material layers, producing effective electrical energy, and possesses an extremely low output impedance, facilitating efficient transmission of the generated electricity.

Using this technology, the research team created an implantable neurological stimulator powered by ultrasound-based energy transmission, eliminating the need for batteries. This was confirmed through experimental validation. In animal model trials, the device was activated even at standard imaging ultrasound levels (500 mW/cm2), imposing minimal strain on the human body. Furthermore, it effectively mitigated symptoms related to abnormal urination caused by overactive bladder disorders through nerve stimulation. (Image credit: Clayton Metz for Virginia Tech)

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