A compact-size and ultrasensitive optical biosensor using a double-spiral microresonator

Anh Igarashi, Yugang Shang, Shigeki Kuroiwa, Keishi Ohashi, Hirohito Yamada

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Citation (Scopus)


A structure of a double-spiral microresonator is demonstrated for high-sensitive biosensing of a microliter sample volume of biomolecules. The microring resonator has been applied as a highly potential label-free biosensor; however, the sensitivity still needs to be improved due to the restriction of the sensing surface. In this report, a resonator with two Si-based spiral waveguides connected by an S-shaped channel is designed to be positioned in a hundred-micrometer-width fluidic channel. The enhanced sensing surface on the same footprint of the double spiral resonator contributes a high bulk sensitivity of about 1,500 nm/RIU, 10-fold more sensitive than the sensitivity of the microring resonators according to 2D-FDTD simulation results. In addition, the fabricated double spiral resonator shows Q-factors of 14,000 in air and 12,000 in water, which doubles that of the conventional microring. The double-spiral structured microresonator can be further applied with a microfluidic channel for detecting changes in biomolecules in real time.

Original languageEnglish
Title of host publication2022 IEEE Sensors, SENSORS 2022 - Conference Proceedings
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781665484640
Publication statusPublished - 2022
Event2022 IEEE Sensors Conference, SENSORS 2022 - Dallas, United States
Duration: 2022 Oct 302022 Nov 2

Publication series

NameProceedings of IEEE Sensors
ISSN (Print)1930-0395
ISSN (Electronic)2168-9229


Conference2022 IEEE Sensors Conference, SENSORS 2022
Country/TerritoryUnited States


  • Double-spiral
  • microresonator
  • sensing surface


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