Microstructured Cantilever Probe on Optical Fiber Tip for Microforce Sensor

Benefiting from the great advances of the femtosecond laser two-photon polymerization(TPP)technology,customized microcantilever probes can be accurately 3-dimensional(3D)manufactured at the nanoscale size and thus have exhibited considerable potentials in the fields of microforce,micro-vibration,and microforce sensors.In this work,a controllable microstructured cantilever probe on an optical fiber tip for microforce detection is demonstrated both theoretically and experimentally.The static performances of the probe are firstly investigated based on the finite element method(FEM),which provides the basis for the structural design.The proposed cantilever probe is then 3D printed by means of the TPP technology.The experimental results show that the elastic constant k of the proposed cantilever probe can be actively tuned from 2.46N/m to 62.35N/m.The force sensitivity is 2.5nm/μN,the Q-factor is 368.93,and the detection limit is 57.43nN.Moreover,the mechanical properties of the cantilever probe can be flexibly adjusted by the geometric configuration of the cantilever.Thus,it has an enormous potential for matching the mechanical properties of biological samples in the direct contact mode.

Overview of refractive index sensors comprising photonic crystal fibers based on the surface plasmon resonance effect[Invited]

Optical fibers have been widely applied to telecommunication,imaging,lasers,and sensing.Among the different types of fibers,photonic crystal fibers(PCFs),also called microstructured optical fibers,characterized by air holes arranged along the length of fibers have experienced tremendous advance due to their unique advantages.They are regarded as a desirable platform to excite surface plasmon resonance(SPR)because of easy realization of phase matching conditions between the fundamental core mode and the plasmonic mode,which plays a critical role in miniaturization and integration of SPR sensors.In this mini-review,the current status of PCF sensors based on SPR is summarized.The theory of SPR is discussed,and simulation methods for PCF-SPR sensors are described.The important parameters including the refractive index detection range,resonance wavelength,and spectral sensitivity responsible for the sensing properties of PCF-SPR sensors are reviewed.The fabrication and the comparison of performances are also illustrated,and,finally,the challenges and future perspectives are outlined.