A 3D-Printed Microforce Sensor for Microscopic Objects

When microscopic objects cannot reliably detect contact forces, they are easily damaged. Traditional microforce sensors based on Micro Electromechanical Systems (MEMS) are limited by their large size, low detection accuracy, and susceptibility to electromagnetic interference.

Wang et al. utilize femtosecond laser-induced two-photon polymerization (TPP) 3D nanoprinting technology with mechanical metamaterials to fabricate the microcantilever tip of a fiber-optic microforce sensor. This sensor can measure the mechanical properties of heterogeneous materials such as cells, useful for biological sample detection and material research.

Optical fiber sensors in the place of traditional MEMS allow for high sensitivity and resistance to electromagnetic interference, without the bulky size required for the complex optical paths in conventional sensors.

“Mechanical metamaterials are designed using precise, unique patterns, resulting in structures that can display desired mechanical properties,” said author Changrui Liao.

The microcantilever tip integrated into the fiber optic sensor uses such metamaterials. The cantilever beam must be accurately aligned to the fiber end face, which is achieved using femtosecond laser-induced TPP 3D nanoprinting. Since the technology is based on the manufacturing principle of layer-by-layer stacking, it dramatically improves the flexibility and formation of microstructure designs.

“We found that the elastic constant k of the fiber-optic micro force sensor can be adjusted by two orders of magnitude,” said Liao. “The cantilever can be tailored to match the mechanical properties of relevant biological specimens.”

The device has achieved a precision of the pico-Newton scale.

“In the future, we would like to conduct both contact and non-contact scanning of samples such as cells or tissues,” said Liao.

Source: “Three-dimensional printed microcantilever with mechanical metamaterial for fiber-optic microforce sensing,” by Famei Wang, Mengqiang Zou, Changrui Liao, Bozhe Li, Dejun Liu, Jie Zhou, Haoqiang Huang, Jinlai Zhao, Chao Liu, Paul K. Chu, and Yiping Wang, APL Photonics (2023). The article can be accessed at https://doi.org/10.1063/5.0159706 .

This paper is part of the Ultrafast Laser Fabrication Enabled Photonics and Devices Collection, learn more here .