title: Flexible heartbeat sensor for wearable device.
abstract: We demonstrate a flexible strain-gauge sensor and its use in a wearable application for heart rate detection. This polymer-based strain-gauge sensor was fabricated using a double-sided fabrication method with polymer and metal, i.e., polyimide and nickel-chrome. The fabrication process for this strain-gauge sensor is compatible with the conventional flexible printed circuit board (FPCB) processes facilitating its commercialization. The fabricated sensor showed a linear relation for an applied normal force of more than 930 kPa, with a minimum detectable force of 6.25Pa. This sensor can also linearly detect a bending radius from 5mm to 100mm. It is a thin, flexible, compact, and inexpensive (for mass production) heart rate detection sensor that is highly sensitive compared to the established optical photoplethysmography (PPG) sensors. It can detect not only the timing of heart pulsation, but also the amplitude or shape of the pulse signal. The proposed strain-gauge sensor can be applicable to various applications for smart devices requiring heartbeat detection.
authors.affiliation: High-tech Materials and Components R&D Division, Korea Electronics Technology Institute, Seongnam, Republic of Korea; Department of Electronics and Information Engineering, Korea University, Sejong, Republic of Korea.
authors.forename: Yeon Hwa
authors.initials: YH
authors.lastname: Kwak
authors.affiliation: High-tech Materials and Components R&D Division, Korea Electronics Technology Institute, Seongnam, Republic of Korea.
authors.forename: Wonhyo
authors.initials: W
authors.lastname: Kim
authors.affiliation: High-tech Materials and Components R&D Division, Korea Electronics Technology Institute, Seongnam, Republic of Korea.
authors.forename: Kwang Bum
authors.initials: KB
authors.lastname: Park
authors.affiliation: High-tech Materials and Components R&D Division, Korea Electronics Technology Institute, Seongnam, Republic of Korea. Electronic address: kimkn@keti.re.kr.
authors.forename: Kunnyun
authors.initials: K
authors.lastname: Kim
authors.affiliation: Department of Electronics and Information Engineering, Korea University, Sejong, Republic of Korea. Electronic address: sseo@korea.ac.kr.
authors.forename: Sungkyu
authors.initials: S
authors.lastname: Seo
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D055096:Optical Devices; D011108:Polymers / Q000737:chemistry*; D000076251:Wearable Electronic Devices
chemical_list: D011108:Polymers
keywords: Flexible; Heartbeat; Sensor; Strain-gauge; Wearable