Open Access
13 March 2021 Globally deployed COVID-19 fever screening devices using infrared thermographs consistently normalize high readings to afebrile range
Conor Healy, Zachary Segal, Chris Hinnerichs, Ethan Ace, Derek Ward, John Honovich
Author Affiliations +
Table 1
Devices stated accuracy and emissivity by type.
IRTs, NCIT, and blackbodies usedTypeStated accuracyStated emissivity
Extech IR200: noncontact forehead infrared thermometerNCIT±0.3°CNA
FLIR E54-EST thermal screening solutionsIRT±0.3°CNA
TVT TD-E2128-TM face recognition terminalIRT±0.3°CNA
Bems temperature terminalIRTNot statedNA
Dahua DH-TPC-BF5421-T thermal hybrid network cameraIRT±0.33°CNA
ZKTeco SF1008+ body temperature + mask detection access control readerIRT±0.33°CNA
Certify SnapXT ProIRT±0.3°CNA
Hikvision DS-2TD2636B-13/P temperature screening thermographic cameraIRT±0.5°CNA
Meridian clear 2 temperature screening KioskIRT±0.5°CNA
Dahua JQ-D70Z blackbodyBB±0.2°C0.97
Sunell SN-TH01 portable blackbodyBB±0.2°C0.97

Fig. 1
Testing configuration for simulated human thermographic reading. (a) Regular image. (b). Thermal image. Subject was mounted at 168 cm from the floor. Manufacturer specifications were followed in the placement of the IRTs relative to the subject. All tablets were mounted at a height of 155 cm and placed at a distance of 50 cm from the subject. The FLIR IRT was mounted at a height of 157.5 cm and placed 70 cm from the subject.

Fig. 2
IRT image of (a) male with normal temperature and (b) male with elevated temperature from IEC 80601.3

Fig. 3
Testing environment. (a) Side view. (b) Top view.

Fig. 4
Testing environment for devices requiring BB calibration with subject and reference device placed side-by-side. (a) Side view. (b) Top view.

Table 2
Deviation from control temperature reading.
DeviceRange (°C)Variance °CMean °CDevice versus subject temp.Difference between device and subject versus subject temp.
Adjusted R-squaredRegression coefficientAdjusted R-squaredRegression coefficient
Control devices
FLIR IRT35 to 402.437.50.9910−0.001
Extech surface NCIT35.05 to 40.052.437.50.9910−0.001
Extech body NCIT36.7 to 40.21.338.20.980.780.8−0.22
Tested devices
Hikvision Bullet IRTa35.6 to 39.61.637.40.990.80.88−0.19
Dahua Bullet IRTb35.4 to 39.41.437.30.990.770.95−0.23
Meridian IRTc36.9 to 39.80.9537.80.910.60.82 (.91 log)d−0.4
ZKTeco IRT36.3 to 39.00.8537.30.940.580.89−0.42
Certify IRT36.4 to 39.00.7237.30.930.530.91−0.47
TVT IRT36.6 to 37.80.1636.−0.78
Bems IRT36.5 to 36.80.00536.70.00100.99−1

Fig. 5
Bland–Altman plot of seven tested devices.

Fig. 6
Recorded readings for tested IRT reading versus subject.

Fig. 7
Bland–Altman plot of Hikvision DS-2TD2636B-13/P Results.

Fig. 8
Bland–Altman plot of Dahua DH-TPC-BF5421-T.

Fig. 9
Bland–Altman plot of Meridian.

Fig. 10
Bland–Altman plot of ZKTeco.

Fig. 11
Bland–Altman plot of Certify.

Fig. 12
Bland–Altman plot of TVT.

Fig. 13
Bland–Altman plot of Bems.

Fig. 14
Disparity between control (FLIR) and tested IRTs: magnitude and direction of deviation from BB reading. (a) Difference between device and subject versus subject. (b) Absolute value of difference between device and subject versus subject.

Fig. 15
Pooled differences between tested devices and BB temperature.

Fig. 16
Results from control devices, FLIR E54-EST and Extech IR200.

Table 3
Variance across measured temperatures by control and tested devices.
DeviceVariance (°C)Mean (°C)Range (°C)
Hypothetical data
BB2.437.535 to 40
Perfect device with no offset2.437.535 to 40
Perfect device with a fixed offset of +12.438.536 to 41
An inaccurate device that does not normalizea3.337.534.4 to 40.7
Experimental data
FLIR2.437.535 to 40
Extech surface mode2.437.535.05 to 40.05
Extech body mode1.338.236.7 to 40.2
Hikvisionb1.637.435.6 to 39.6
Dahuac1.437.335.4 to 39.4
Meridiand0.9537.836.9 to 39.8
ZKTeco0.8537.336.3 to 39.0
Certify0.7237.336.4 to 39.0
TVT0.1636.936.6 to 37.8
Bems0.00536.736.5 to 36.8

Table 4
Laboratory humidity and temperature conditions in each trial by device.
Device tested in trialMinimum temperature (°C)Maximum temperature (°C)Minimum humidity (%)Maximum humidity (%)

Fig. 17
Results from Hikvision DS-2TD2636B-13/P.

Fig. 18
Results from Dahua DH-TPC-BF5421-T.

Fig. 19
Results from Meridian Clear 2.

Fig. 20
Results from Certify SnapXT Pro.

Fig. 21
Results from ZKTeco SF1008+.

Fig. 22
Results from TVT TD-E2128-TM.

Fig. 23
Results from Bems. Logo
Cited by 5 scholarly publications.
Temperature metrology

Infrared radiation

Control systems


Body temperature

Forward looking infrared


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