Detection-gap-independent optical sensor design using divergence-beam-controlled slit lasers for wearable devices

Young Zoon Yoon, Hyochul Kim, Yeonsang Park, Jineun Kim, Min Kyung Lee, Un Jeong Kim, Young Geun Roh, Sung Woo Hwang

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

Abstract

Wearable devices often employ optical sensors, such as photoplethysmography sensors, for detecting heart rates or other biochemical factors. Pulse waveforms, rather than simply detecting heartbeats, can clarify arterial conditions. However, most optical sensor designs require close skin contact to reduce power consumption while obtaining good quality signals without distortion. We have designed a detection-gap-independent optical sensor array using divergence-beam-controlled slit lasers and distributed photodiodes in a pulse-detection device wearable over the wrist's radial artery. It achieves high biosignal quality and low power consumption. The top surface of a vertical-cavity surface-emitting laser of 850 nm wavelength was covered by Au film with an open slit of width between 500 nm and 1500 nm, which generated laser emissions across a large divergence angle along an axis orthogonal to the slit direction. The sensing coverage of the slit laser diode (LD) marks a 50% improvement over nonslit LD sensor coverage. The slit LD sensor consumes 100% more input power than the nonslit LD sensor to obtain similar optical output power. The slit laser sensor showed intermediate performance between LD and light-emitting diode sensors. Thus, designing sensors with multiple-slit LD arrays can provide useful and convenient ways for incorporating optical sensors in wrist-wearable devices.

Original languageEnglish
Title of host publicationInfrared Sensors, Devices, and Applications VI
EditorsAshok K. Sood, Paul D. LeVan, Priyalal Wijewarnasuriya, Arvind I. D'Souza
PublisherSPIE
ISBN (Electronic)9781510603394
DOIs
StatePublished - 2016
EventInfrared Sensors, Devices, and Applications VI - San Diego, United States
Duration: 31 Aug 20161 Sep 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9974
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceInfrared Sensors, Devices, and Applications VI
Country/TerritoryUnited States
CitySan Diego
Period31/08/161/09/16

Keywords

  • detection gap
  • lasers
  • Optical sensor
  • photoplethysmography
  • slit lasers
  • wrist-wearable devices

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