The development of high-response quartz crystal microbalance (QCM) humidity sensors typically requires the use of substantial amounts of moisture-sensitive materials, which can lead to slow response and recovery times, as well as inadequate hysteresis performance. In this study, a humidity sensor based on a high fundamental frequency (19.6 MHz) QCM transducer is prepared with fullerenol (C60-OH) nanodot-modified Ti3C2TX as the moisture-sensitive material. With only a tiny amount (1 μg) of material coated, the prepared high-frequency (19.6 MHz) QCM sensor exhibits an unexpectedly strong response to humidity, manifesting a maximum frequency shift up to −12,839 Hz in the range of 2–97 % RH, which is 10 times higher than a low-frequency (10 MHz)-based QCM sensor. Additionally, high-frequency (19.6 MHz) QCM sensor demonstrates excellent sensing performance in low humidity, with a sensitivity of −40.2 Hz/%RH in the range of 0.2–10 % RH. This high response is primarily ascribed to low initial mass of high fundamental frequency QCM and the improvement in moisture-sensing capabilities of Ti3C2TX due to the incorporation of C60-OH. With its outstanding properties, the high-frequency QCM sensor holds great potential for application in human-machine interaction.
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