We exploit the premises of exceptional points of degeneracy (EPDs) induced in linear time-periodic (LTP) systems to achieve extremely sensitive biosensors. The EPD is formed in a single LC resonator where the total capacitance is comprised of a time-varying capacitor in parallel to a biosensing capacitor. We use the time-periodic variation of a system parameter (e.g., capacitance) to achieve a second order EPD aiming at improving the sensitivity of liquid based radio frequency biosensors, leading to an intrinsic ultra sensitivity. We show the emergence of EPDs in such a system and the ultra sensitivity of the degenerate resonance frequency to perturbations compared to conventional RF sensors. Moreover, we investigate the capacitance and conductance variations of an interdigitated biosensing capacitor to the changes in the concentration of a biological material under test (MUT), leading to subsequent large changes in the resonance frequency of the LTP-LC resonator. A comparison with a standard LC resonator demonstrates the ultra-high sensitivity of the proposed LTP-LC based biosensor. In addition, we show the scalability of the biosensor sensitivity across different frequency ranges.

The human body exhibits complex, spatially distributed chemo-electro-mechanical processes that must be properly captured for emerging applications in virtual/augmented reality, precision health, activity monitoring, bionics, and more. A key factor in enabling such applications involves the seamless integration of multipurpose wearable sensors across the human body in different environments, spanning from indoor settings to outdoor landscapes. Here, we report a versatile epidermal body area network ecosystem that enables wireless power and data transmission to and from battery-free wearable sensors with continuous functionality from dry to underwater settings. This is achieved through an artificial near field propagation across the chain of biocompatible, magneto-inductive metamaterials in the form of stretchable waterborne skin patches—these are fully compatible with pre-existing consumer electronics. Our approach offers uninterrupted, self-powered communication for human status monitoring in harsh environments where traditional wireless solutions (such as Bluetooth, Wi-Fi or cellular) are unable to communicate reliably.

Common digestive and lung disorders such as stomach problems and pleural emission pose serious difficulties for patients who undergo open surgeries wherein a wirelessly powered swimming microrobot has the potential for minimally invasive missions from diagnosis to drug delivery and surgery. However, remote steering toward an arbitrary destination is yet a challenge to existing microrobots. Here, a resonant wireless power transfer system is incorporated into an array of planar coils to generate spatio-temporal patterns of magnetic fields on an untethered swimming microrobot. It is shown this generates an effective Lorentz force on the microrobot's power receptor coil. Automated switching of the array current creates a traveling magnetic pattern that enables smooth microrobot steering and controls its velocity. This eliminates the need for embedded magnets and shielding materials that suffer from nonlinear characteristics. The microrobot's function is validated by an in-vitro experiment that mimics the anatomy of the stomach filled with fluid at a centimeter range underneath the skin. Our microrobot with a mass of 7 g is able to reach the velocity of 0.45 mm/s in a controlled direction by applying a small peak magnetic field of 2.15 mT at 96 kHz. The propelling force is proportional to the square of the total magnetic field's intensity and can be enormously increased depending on the application. Compared to microrobots with similar dimensions, this method results in a 50-fold increased ratio of propelling force to applied magnetic energy, which is suitable for carrying heavier payloads to farther locations.