Temperature compensated strain sensor in fused silica by femtosecond laser inscription

Abstract

Measuring strain without parasitic thermal influence is vital. A temperature compensated strain sensor is fabricated in fused silica using femtosecond laser micromachining. Utilizing femtosecond laser direct writing and femtosecond irradiation followed by chemical etching, two Bragg gratings are fabricated in the bulk of a fused silica substrate. By suspending one of the Bragg gratings in a cantilever, it is mechanically isolated from the rest of the substrate. Thermal and tensile characterization showed that both Bragg gratings are sensitive to thermal changes with a sensitivity around 10.5 pm/ • C, while only the non-isolated Brag grating is sensitive to strain with a sensitivity of 1.1 pm/µϵ. Hence, it is proven that the parasitic thermal influence on the strain sensor can be compensated by taking into account the response of the isolated Bragg grating.

Influence of Laser Power on Achieving Ultra Low Stiffness in Resistive Strain Gauges Through on Laser Bonding Transfer‐Patterning of Multiwall Carbon Nanotubes (MWCNTs) onto Polydimethylsiloxane (PDMS) Film

“…From the Equation (3) the change in temperature depends on the laser parameters used during the laser irradiation process. [15] Considering that the linear dependence at high temperature is probably characteristic of such a high degree of excitation of the vibrational modes, and based on the requirement of the third law of thermodynamics that the derivative of any elastic constant concerning temperature must approach zero as the temperature approaches absolute zero, and proposed an empirical formula of temperature-dependent Young's modulus. [16] E where, E 0 is Young's modulus of untreated material (at absolute zero), and B is the slope of Young's modulus-temperature curve at high temperatures depending on the laser power used.…”