Maintaining stillness during bioelectrical signal acquisition is crucial, but breathing noise remains a challenge. Isotropic adhesives, commonly used, leave residues affecting accuracy. This paper proposes a Janus adhesive hydrogel with selective frequency damping to mitigate this issue. The hydrogel shows a 60-fold greater damping effect at breathing frequencies (0.1-1 Hz) than at other frequencies and exhibits an asymmetric adhesion difference of up to 537 times, preventing residues. Stable signal transmission over 10,000 cycles is achieved. Clinical trials demonstrate its effectiveness in diagnosing otitis media with higher sensitivity than invasive probes and in polysomnography for obstructive sleep apnea diagnosis.
