A passive resonant sensor with kirigami patterning is presented to wirelessly report material deformation in closed systems. The sensors are fabricated from copper‐coated polyimide by etching a conductive Archimedean spiral and then laser cutting kirigami patterns. The sensor response is defined as the resonant frequency in the transmission scattering parameter signal (S21), which is captured via a benchtop vector network analyzer. The sensors are tested over a 0–22 cm range of extension and show a significant shift in resonant frequency (e.g., 90 MHz shift for 10 cm stretch). Furthermore, the effect of resonator coil pitch on the extension sensor gain (MHz cm−1) and linear span of the sensor is studied. The repeatability of the sensor gain is confirmed by performing hysteresis cycles. The sensors is coated with polydimethylsiloxane films to protect from electrical shorting in aqueous environments. The coated resonators are placed in a pipe to report flow rates. The sensor with 1 mm coating is found to have the largest gain (0.17 MHz⋅s mL−1) and linear span (10–100 mL s−1). Thus, flexible resonant sensors with kirigami‐inspired patterns can be tuned via geometric and coating considerations to wirelessly report a large range of extension lengths for potential uses in health monitoring, motion tracking, deformation detection, and soft robotics.

Carbon supports have been shown to provide better hydrothermal stability than alumina or silica supports, thus attracting more attention for aqueous-phase biomass conversion reactions.

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Inexpensive and accurate tools for monitoring conditions in enclosed environments (through garments, bandages, tissue, etc.) have been a long-standing goal of medicine. Passive resonant sensors are a promising solution for such wearable health sensors as well as off-body diagnostics. They are simple circuits with inherent inductance and capacitance (LC tank) that have a measurable resonant frequency. Changes in local parameters, e.g., permittivity or geometry, effect inductance and capacitance which cause a resonant frequency shift response. This signal transduction has been applied to several biomedical applications such as intracranial pressure, hemodynamics, epidermal hydration, etc. Despite these many promising applications presented in the literature, resonant sensors still do not see widespread adoption in biomedical applications, especially as wearable or embedded sensing devices. This perspective highlights some of the current challenges facing LC resonant sensors in biomedical applications, such as positional sensitivity, and potential strategies that have been developed to overcome them. An outlook on adoption in medicine and health monitoring is presented, and a perspective is given on next steps for research in this field.