Fiber‐Integrated Force Sensor using 3D Printed Spring‐Composed Fabry‐Perot Cavities with a High Precision Down to Tens of Piconewton

Abstract Developing microscale sensors capable of force measurements down to the scale of piconewtons is of fundamental importance for a wide range of applications. To date, advanced instrumentations such as atomic force microscopes and other specifically developed micro/nano‐electromechanical systems face challenges such as high cost, complex detection systems and poor electromagnetic compatibility. Here, it presents the unprecedented design and 3D printing of general fiber‐integrated force sensors using spring‐composed Fabry‐Perot cavities. It calibrates these microscale devices employing varied‐diameter m‐scale silica particles as standard weights. The force sensitivity and resolution reach values of (0.436 ± 0.007) nmnN^‐1 and (40.0 ± 0.7) pN, respectively, which are the best resolutions among all fiber‐based nanomechanical probes so far. It also measured the non‐linear airflow force distributions produced from a nozzle with an orifice of 2 m, which matches well with the full‐sized simulations. With further customization of their geometries and materials, it anticipates the easy‐to‐use force probe can well extend to many other applications such as air/fluidic turbulences sensing, micro‐manipulations, and biological sensing.