title: A novel autonomic activation measurement method for stress monitoring: non-contact measurement of heart rate variability using a compact microwave radar.
abstract: We developed a novel method for non-contact monitoring of stress-induced autonomic activation through the back of a chair, using a compact 24 GHz microwave radar (8 x 5 x 3 cm), without large-scale equipment and placing a heavy burden on the monitored individual. Following a silent period of 120 s, audio stimuli using a composite tone of 2,120 and 2,130 Hz sine-waves at 95 dB were conducted for 120 s. From dorsal, LF/HF of HRV reflecting sympatho-vagal balance was determined by microwave radar with the maximum entropy method using eight volunteers (mean age 23 +/- 1 years). Mean LF/HF measured by non-contact and contact (using electrocardiography for reference) methods during audio stimuli increased 34 and 37%, respectively, as compared with those of the silent period. Maximum cross-correlations between contact and non-contact measurements averaged 0.73 +/- 0.10. Our method appears to be promising for future monitoring of stress-induced autonomic activation of operators and may reduce stress-induced accidents.
authors.affiliation: Department of Management Systems Engineering, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo, 191-0065, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Suzuki
authors.forename: Takemi
authors.initials: T
authors.lastname: Matsui
authors.forename: Hayato
authors.initials: H
authors.lastname: Imuta
authors.forename: Maki
authors.initials: M
authors.lastname: Uenoyama
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yura
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ishihara
authors.forename: Mitsuyuki
authors.initials: M
authors.lastname: Kawakami
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D004562:Electrocardiography; D006339:Heart Rate; D006801:Humans; D008872:Microwaves; D008991:Monitoring, Physiologic / Q000379:methods; D011825:Radar; D013312:Stress, Physiological