Millimeter-scale magnetic implants paired with a fully integrated wearable device for wireless biophysical and biochemical sensing

TLDR

Implantable sensors can directly interface with various organs for precise health evaluation, yet signal extraction usually requires transcutaneous wires, IC chips, or bulky readout equipment, raising infection risk, reducing biocompatibility, or limiting portability. We develop millimeter‑scale, chip‑less, battery‑less magnetic implants paired with a fully integrated wearable device to measure biophysical and biochemical signals. The wearable induces large‑amplitude damped vibrations in the magnetic implants and wirelessly captures their motions, which reflect surrounding biophysical conditions and biochemical concentrations depending on surface modification. In rat models, the system measures cerebrospinal fluid viscosity, intracranial pressure, and CSF glucose, demonstrating continuous, wireless monitoring of diverse biophysical and biochemical conditions.

Abstract

Implantable sensors can directly interface with various organs for precise evaluation of health status. However, extracting signals from such sensors mainly requires transcutaneous wires, integrated circuit chips, or cumbersome readout equipment, which increases the risks of infection, reduces biocompatibility, or limits portability. Here, we develop a set of millimeter-scale, chip-less, and battery-less magnetic implants paired with a fully integrated wearable device for measuring biophysical and biochemical signals. The wearable device can induce a large amplitude damped vibration of the magnetic implants and capture their subsequent motions wirelessly. These motions reflect the biophysical conditions surrounding the implants and the concentration of a specific biochemical depending on the surface modification. Experiments in rat models demonstrate the capabilities of measuring cerebrospinal fluid (CSF) viscosity, intracranial pressure, and CSF glucose levels. This miniaturized system opens the possibility for continuous, wireless monitoring of a wide range of biophysical and biochemical conditions within the living organism.