This paper presents the sensitivity characteristics of a microelectromechanical systems (MEMS) piezoresistive cantilever and nanohole array used in a waterproof airflow sensor. Previously, a Pitot tube-type waterproof airflow sensor was developed for seabird biologging. Built-in MEMS piezoresistive cantilevers are used as the differential pressure sensing elements. The waterproof function is achieved using nanohole arrays via Laplace pressure. However, the mechanism underlying sensitivity reduction when nanohole arrays are attached is unclear. Here, we experimentally and theoretically verified that the specific constant, which determines the airflow rate through the cantilever and nanohole array, affects sensitivity reduction. An airflow sensor with a small sensitivity reduction was achieved based on the calculated results using an appropriate cantilever and nanohole arrays. We demonstrated that the proposed method for estimating the sensitivity reduction is useful for designing waterproof airflow sensors using cantilever-type differential pressure sensor elements.

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Even though the toughness of hydrogels is usually adjusted by changing the cross-linking density and structure, or the polymer concentration, we have discovered a new strategy to control the toughness...

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