Biodegradable Frequency‐Selective Magnesium Radio‐Frequency Microresonators for Transient Biomedical Implants

Bioresorbable implantable medical devices show a great potential for applications requiring medical care over well‐defined periods of time. Once their function is fulfilled, such implants naturally degrade and resorb in the body, which eliminates adverse long‐term effects or the need for a secondary surgery to extract the implanted device. Since biodegradable materials are water‐soluble, the fabrication of such transient electronic circuits and devices requires special care and needs to rely solely on dry processing steps without exposure to aqueous solutions. A further challenge is the in vivo powering of medical implants that are only constituted of biodegradable materials. This paper describes the design, fabrication, and testing of radio‐frequency biodegradable magnesium microresonators. To this end, an innovative microfabrication process with minimal exposure to aqueous media is developed to fabricate magnesium‐based, water‐soluble electronic components. It consists of a novel sequence of only three steps: one physical vapor deposition, one photolithography, and one ion beam etching step. The frequency‐selective wireless heating of different resonators is demonstrated. This represents a significant step toward their use as power receivers and microheaters in biodegradable implantable medical devices, for applications such as triggered drug release.