Built on research.
Built on research.
Expanding what we know.
Expanding what we know.
Peer-reviewed research from our pilot study, with an expanded clinical study underway.
Peer-reviewed research from our pilot study
with an expanded clinical study underway.
Peer-reviewed research from our pilot study, with an expanded clinical study underway.
The literature
The literature
The relationship between reproductive hormones and thermoregulation has been established in peer-reviewed research spanning decades. One strand of that research used invasive sensors to show that core body temperature patterns shift in real-time with hormonal changes leading up to ovulation. Phira was built to capture the same patterns non-invasively, and to extend it across the full cycle, tracking those thermoregulatory shifts continuously as a window into your underlying hormonal trends. The following studies form the scientific foundation of this approach.
The literature
The relationship between reproductive hormones and thermoregulation has been established in peer-reviewed research spanning decades. One strand of that research used invasive sensors to show that core body temperature patterns shift in real-time with hormonal changes leading up to ovulation. Phira was built to capture the same patterns non-invasively, and to extend it across the full cycle, tracking those thermoregulatory shifts continuously as a window into your underlying hormonal trends. The following studies form the scientific foundation of this approach.
N. Charkoudian and N. S. Stachenfeld, "Reproductive hormone influences on thermoregulation in women," Comprehensive Physiology, vol. 4, no. 2, pp. 793-804, April 2014.
N. Charkoudian and N. S. Stachenfeld, "Reproductive hormone influences on thermoregulation in women," Comprehensive Physiology, vol. 4, no. 2, pp. 793-804, April 2014.
N. Charkoudian and N. S. Stachenfeld, "Reproductive hormone influences on thermoregulation in women," Comprehensive Physiology, vol. 4, no. 2, pp. 793-804, April 2014.
P.-A. Regidor, M. Kaczmarczyk, E. Schiweck, M. Goeckenjan-Festag, and H. Alexander, "Identification and prediction of the fertile window with a new web-based medical device using a vaginal biosensor for measuring the circadian and circamensual core body temperature," Gynecological Endocrinology, vol. 34, no. 3, pp. 256–260, 2018.
P.-A. Regidor, M. Kaczmarczyk, E. Schiweck, M. Goeckenjan-Festag, and H. Alexander, "Identification and prediction of the fertile window with a new web-based medical device using a vaginal biosensor for measuring the circadian and circamensual core body temperature," Gynecological Endocrinology, vol. 34, no. 3, pp. 256–260, 2018.
P.-A. Regidor, M. Kaczmarczyk, E. Schiweck, M. Goeckenjan-Festag, and H. Alexander, "Identification and prediction of the fertile window with a new web-based medical device using a vaginal biosensor for measuring the circadian and circamensual core body temperature," Gynecological Endocrinology, vol. 34, no. 3, pp. 256–260, 2018.
A. Roy Phillips, A. Teimouri, F. Olivera-Rial, S. De, and A. Menon, "Physiological signal characterization from an earring-back wearable," in The Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2026), Toronto, ON, Canada, July 2026.
A. Roy Phillips, A. Teimouri, F. Olivera-Rial, S. De, and A. Menon, "Physiological signal characterization from an earring-back wearable," in The Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2026), Toronto, ON, Canada, July 2026.
A. Roy Phillips, A. Teimouri, F. Olivera-Rial, S. De, and A. Menon, "Physiological signal characterization from an earring-back wearable," in The Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2026), Toronto, ON, Canada, July 2026.
Phira's pilot study
Phira's pilot study
Our IRB-approved clinical pilot study conducted over multiple months in a diverse, free-living cohort represents the first systematic characterization of physiological signals from the posterior ear location across the menstrual cycle and establishes the posterior ear as a novel and reliable site for advanced physiological monitoring. This data powers our proprietary hormone tracking engine, mapping these signals to hormone patterns.
31 cycles
from 12 women, free-living
from 12 women, free-living
27 – 36 days
Subject cycle length range
Subject cycle length range
24/7
Posterior ear thermal monitoring
Posterior ear thermal monitoring
VALIDATED AGAINST
Daily urine-based hormone testing
Clinically-validated sleep wearable
Clinically-validated ovulation confirmation application
VALIDATED AGAINST
Daily urine-based hormone testing
Clinically-validated sleep wearable
Clinically-validated ovulation confirmation application
Our peer-reviewed foundational paper, Physiological Signal Characterization from an Earring-back Wearable, was presented at the IEEE Engineering in Medicine and Biology Conference (EMBC), July 2026.
Our peer-reviewed foundational paper, Physiological Signal Characterization from an Earring-back Wearable, was presented at the IEEE Engineering in Medicine and Biology Conference (EMBC), July 2026.
Phira's pilot study
Our IRB-approved clinical pilot study conducted over multiple months in a diverse, free-living cohort represents the first systematic characterization of physiological signals from the posterior ear location across the menstrual cycle and establishes the posterior ear as a novel and reliable site for advanced physiological monitoring. This data powers our proprietary hormone tracking engine, mapping these signals to hormone patterns.
31 cycles
from 12 women, free-living
27 – 36 days
Subject cycle length range
24/7
Posterior ear thermal monitoring
VALIDATED AGAINST
Daily urine-based hormone testing
Clinically-validated sleep wearable
Clinically-validated ovulation confirmation application
Our peer-reviewed foundational paper, Physiological Signal Characterization from an Earring-back Wearable, was presented at the IEEE Engineering in Medicine and Biology Conference (EMBC), July 2026.
Figure 1. Thermal features captured continuously from the posterior ear location during our pilot study, demonstrating patterns consistent with established estrogen, LH, and progesterone dynamics [1] across the menstrual cycle. Expanded clinical study in progress.
[1] M. Häggström, “Reference ranges for estradiol, progesterone, luteinizing hormone and follicle-stimulating hormone during the menstrual cycle,” WikiJournal of Medicine, vol. 1, no. 1, 2014.
Figure 1. Thermal features captured continuously from the posterior ear location during our pilot study, demonstrating patterns consistent with established estrogen, LH, and progesterone dynamics [1] across the menstrual cycle. Expanded clinical study in progress.
[1] M. Häggström, “Reference ranges for estradiol, progesterone, luteinizing hormone and follicle-stimulating hormone during the menstrual cycle,” WikiJournal of Medicine, vol. 1, no. 1, 2014.
Results: real-time tracking of hormone dynamics
Figure 1. Biomarkers captured continuously from the posterior ear location during our pilot study, demonstrating patterns consistent with established estrogen, LH, and progesterone dynamics [1] across the menstrual cycle. Expanded clinical study in progress.
[1] M. Häggström, “Reference ranges for estradiol, progesterone, luteinizing hormone and follicle-stimulating hormone during the menstrual cycle,” WikiJournal of Medicine, vol. 1, no. 1, 2014.
Our study is expanding.
Our study is expanding.
We're looking for participants.
We're currently enrolling women for our expanded study, which includes broader demographics and more cycle diversity, to demonstrate that the estrogen, LH, and progesterone dynamics we've already captured extend across a wider population.
We're currently enrolling women for our expanded study, which includes broader demographics and more cycle diversity, to demonstrate that the estrogen, LH, and progesterone dynamics we've already captured extend across a wider population.