Single-molecule optofluidic microsensor with interface whispering gallery modes

Xiao-Chong Yu; Shui-Jing Tang; Wenjing Liu; Yinglun Xu; Qihuang Gong; You-Ling Chen; Yun-Feng Xiao

doi:10.1073/pnas.2108678119

Single-molecule optofluidic microsensor with interface whispering gallery modes

Proc Natl Acad Sci U S A. 2022 Feb 8;119(6):e2108678119. doi: 10.1073/pnas.2108678119.

Authors

Xiao-Chong Yu^{1

2

3

4}, Shui-Jing Tang^{1

2}, Wenjing Liu^{1

2}, Yinglun Xu^{1

2}, Qihuang Gong^{1

2}, You-Ling Chen⁵, Yun-Feng Xiao^{6

2

7

8

9}

Affiliations

¹ State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China.
² Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China.
³ Department of Physics, Beijing Normal University, Beijing 100875, China.
⁴ Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China.
⁵ State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China; yfxiao@pku.edu.cn ylchen@semi.ac.cn.
⁶ State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China; yfxiao@pku.edu.cn ylchen@semi.ac.cn.
⁷ Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China.
⁸ Yangtze Delta Institute of Optoelectronics, Peking University, Nantong 226010, China.
⁹ National Biomedical Imaging Center, Peking University, Beijing 100871, China.

Abstract

Label-free sensors are highly desirable for biological analysis and early-stage disease diagnosis. Optical evanescent sensors have shown extraordinary ability in label-free detection, but their potentials have not been fully exploited because of the weak evanescent field tails at the sensing surfaces. Here, we report an ultrasensitive optofluidic biosensor with interface whispering gallery modes in a microbubble cavity. The interface modes feature both the peak of electromagnetic-field intensity at the sensing surface and high-Q factors even in a small-sized cavity, enabling a detection limit as low as 0.3 pg/cm² The sample consumption can be pushed down to 10 pL due to the intrinsically integrated microfluidic channel. Furthermore, detection of single DNA with 8 kDa molecular weight is realized by the plasmonic-enhanced interface mode.

Keywords: interfacial molecular detection; optofluidic biosensor; whispering gallery microresonator.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biosensing Techniques / methods*
Microfluidics / methods*
Nanotechnology / methods