Fiber-TipPolymer Microcantilever for Fast and HighlySensitive Hydrogen Measurement

Hydrogen as an antioxidant gas has been widely used in medical and biological fields for preventing cancer or for treating inflammation. However, controlling the hydrogen concentration is crucial for the practical use due to its explosive property when its volume concentration in air reaches the explosive limit (4%). In this work, a polymer based microcantilever (μ-cantilever) hydrogen sensor located at the end of a fiber tip is proposed to detect hydrogen concentration in medical and biological applications. The proposed sensor was developed using femtosecond (FS) laser-induced two-photon polymerization (TPP) to print the polymer μ-cantilever, and magnetron sputtering to coat a palladium (Pd) film on the upper surface of the μ-cantilever. Such a device exhibits a high sensitivity, roughly 2 nm %-1 when the hydrogen concentration rises from 0% to 4.5%(v/v) and a short response time, around 13.5 s at 4%(v/v), making it suitable for medical and environmental application. In addition to providing an ultra-compact optical solution for fast and highly sensitive hydrogen measurement, the polymer μ-cantilever fiber sensor can be used for diverse medical and biological sensing applications by replacing Pd with other functional materials.