Continuous temperature monitoring by flexible hydrogel‐based electronics achieves rapid advances, overcoming the drawbacks of rigid and unportable thermocouples. However, an open question is whether and how the thermosensitive hydrogel designing can prevent mechanical mismatching between devices and skin‐tissues and reduces interfacial failure. Herein, a versatile hydrogel‐based thermistor epidermal sensor (HTES) paradigm is engineered consisting of thermosensitive and self‐adhesive function layer (PEST) in tandem with a surface spraying Ag interdigital electrode. Leveraging the advantage of catechol chemistry inspired tannic acid‐coated cellulose nanocrystals, the resultant PEST achieves the adhesion‐cohesion equilibrium along with superior thermosensitivity. The assembled HTES thereby yields unprecedented features of superior thermosensitivity (TCR = 1.43% °C−1), exceptional mechanical integrity (hammering 200 cycles, current variation <9%), impressive interfacial compatibility (adhesion strength, 25 kPa), and environmental stability (thermosensation retention of 98% over 5 days). By in‐situ microstructure observation, the unique geometrical synchronization of HTES with arbitrary curvilinear surfaces (e.g., sphere, cone, and saddle) stemming from elastic dissipation and discrete rupture of the adhesive fibrillar bridges is validated, affording competitive advantages than that of the state‐of‐the‐art thermistor electronics for alleviating the interfacial deterioration, which dramatically inspires advanced HTES design strategies and paves the way for commercialization of attachable thermistor electronics.

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This paper reports on the successful preparation of LaPO4-x wt.% LiF (x = 0–5) ceramics using the traditional solid-state reaction method. The crystal structures, sintering behaviors, and dielectric response at microwave and terahertz frequencies were investigated. XRD results indicate that all the diffraction peaks were attributed to LaPO4, and no secondary phase was observed. Rietveld refinement was conducted to analyze the variation of the crystal structure of LaPO4-x wt.% LiF. SEM indicates that the addition of LiF significantly decreased the grain size while increasing the apparent density of the ceramics. When x = 3, the optimum microwave dielectric properties εr = 10.03, Q × f = 81,467 GHz, and τf = −43.79 ppm/°C were achieved in LaPO4-3 wt.% LiF ceramic at 750 °C. The infrared reflectance spectrum and terahertz time-domain spectroscopy were analyzed and compared with the dielectric properties measured at microwave frequency to investigate the inherent dielectric response. The findings indicate that the dielectric constant attributed to ionic displacement polarization and oxygen vacancy is an essential factor affecting dielectric loss. Moreover, it is worth noting that the LaPO4-3 wt.% LiF ceramic demonstrates excellent compatibility with silver powders, suggesting its immense potential as a dielectric material in LTCC applications.