Body Temperature Software (BTS)

K243778 · Fitbit, LLC · QZA · Feb 13, 2025 · General Hospital

Device Facts

• Record ID: K243778
• Device Name: Body Temperature Software (BTS)
• Applicant: Fitbit, LLC
• Product Code: QZA · General Hospital
• Decision Date: Feb 13, 2025
• Decision: SESE
• Submission Type: Special
• Regulation: 21 CFR 880.2915
• Device Class: Class 2
• Attributes: Software as a Medical Device, Pediatric

Indications for Use

The Body Temperature Software (BTS) App is a software-only mobile medical application intended for over-the-counter (OTC) use with compatible mobile computing platforms that includes a general purpose infrared sensor for the intermittent determination of human body temperature on people of all ages.

Device Story

BTS is a SaMD mobile application using a smartphone's integrated infrared sensor to measure temporal artery temperature. User performs a forehead sweep; app processes infrared signal data to estimate rectal temperature. Operation: user-guided non-contact sweep from forehead center to temple. App performs pre-measurement signal quality checks (e.g., sensor temperature, skin temperature, window temperature) using binary flags to ensure valid data collection. Output: body temperature value displayed to user; optional color-coded guide for interpretation. Used in home/general environments by adults. Benefits: provides on-demand, non-invasive body temperature monitoring.

Clinical Evidence

No clinical data. Bench testing only. Laboratory accuracy demonstrated ±0.3°C per ISO 80601-2-56. Software verification confirmed functionality of binary flag modifications.

Technological Characteristics

SaMD; infrared sensing principle; polynomial algorithm for rectal temperature approximation. Compatible with consumer smartphones (e.g., Google Pixel). Operates in ambient 15°C-35°C. Accuracy ±0.3°C. Software verification and risk management per ISO 14971.

Indications for Use

Indicated for intermittent determination of human body temperature in people of all ages, excluding premature/preterm infants. Intended for OTC use by individuals 18+ years of age on themselves or others.

Regulatory Classification

Identification

Body temperature sensing software is a software device used for the determination of human body temperature by means of analyzing input sensor data. The Body Temperature Software (BTS) App is a software-only mobile medical application intended for over-the-counter (OTC) use with compatible mobile computing platforms that includes a general purpose infrared sensor for the intermittent determination of human body temperature on people of all ages.

Special Controls

In combination with the general controls of the FD&C Act. the body temperature sensing software is subject to the following special controls:

Predicate Devices

• Body Temperature Software (BTS) (DEN230050)

Submission Summary (Full Text)

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February 13, 2025

Fitbit LLC Nathan Austin Lead Regulatory Affairs Technical Program Manager 215 Fremont St San Francisco, California 94105

Re: K243778

Trade/Device Name: Body Temperature Software (BTS) Regulation Number: 21 CFR 880.2915 Regulation Name: Body Temperature Sensing Software Regulatory Class: Class II Product Code: QZA Dated: December 4, 2024 Received: December 9, 2024

Dear Nathan Austin:

We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device"

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(https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).

Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30. Design controls; 21 CFR 820.90. Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review. the OS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.

All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rue"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-devices/device-advicecomprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email ([e-mail]) or phone [phone] or 301-796-7100).

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Sincerely,

Porsche Bennett

Porsche Bennett For David Wolloscheck Ph.D. Assistant Director DHT3C: Division of Drug Delivery and General Hospital Devices, and Human Factors OHT3: Office of Gastrorenal, ObGyn, General Hospital, and Urology Devices Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

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# Indications for Use

510(k) Number (if known) K243778

Device Name Body Temperature Software (BTS)

#### Indications for Use (Describe)

The Body Temperature Software (BTS) App is a software-only mobile medical application intended for over-the- counter (OTC) use with compatible mobile computing platforms that includes a general purpose infrared sensor for the intermittent determination of human body temperature on people of all ages.

| Type of Use (Select one or both, as applicable) | |
|-------------------------------------------------|--|
|-------------------------------------------------|--|

Prescription Use (Part 21 CFR 801 Subpart D)

|X | Over-The-Counter Use (21 CFR 801 Subpart C)

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### K243778- 510k Summary

This Premarket Notification is submitted by:

Fitbit, LLC. 215 Fremont Street, San Francisco, CA 94105

## Contact Information:

Contact Person: Nathan Austin Phone: [phone] Email: [e-mail] Date Prepared: February 13, 2025

### Device Trade Name: Body Temperature Software (BTS)

| Subject Device Information | |
|----------------------------------|-----------------------------------|
| Device Classification Name | Body temperature sensing software |
| Review Panel | General Hospital |
| Product Code & Regulation Number | QZA - 21 CFR 880.2915 |
| Regulatory Class | Class II |
| 510k Number | K243778 |

#### Predicate Device:

The legally marketed predicate for the subject device is detailed in the table below.

| Predicate Device<br>Trade Name | De Novo | Product Code | Manufacturer |
|------------------------------------|-----------|--------------|--------------|
| Body Temperature<br>Software (BTS) | DEN230050 | QZA | Fitbit LLC |

#### Indications for Use:

The Body Temperature Software (BTS) App is a software-only mobile medical application intended for over-the-counter (OTC) use with compatible mobile computing platforms that includes a general purpose infrared sensor for the intermittent determination of human body temperature on people of all ages.

#### Device Description:

The Body Temperature Software ("BTS") mobile application ("App"), is a Software as a Medical Device (SaMD) that leverages an infrared sensor from qualified compatible general computing platforms (i.e. Google Pixel Smartphone) to provide on-demand body temperature measurements. The BTS App is based on well understood infrared measurement technology. The app leverages consumer general purpose computing platforms to collect the inputs for measurement.

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The BTS App is intended to be operated by users above 18 years of age and can be used to measure body temperature for themselves or other individuals. To collect the input temperature data, the user is guided to conduct a non-contact forehead sweep starting at the center of the forehead and ending at the temple, thereby passing over the temporal artery, which corresponds to the highest temperature point on the forehead. This temperature data is then used as an input into the BTS App to convert the measured skin temperature data into a body temperature value. Before and during this measurement process, the BTS App performs a series of signal quality checks to ensure the validity of the temperature data collected. Additionally, to aid users with the interpretation of their measurements, the BTS App also has the option to present users with a color-coded temperature quide to indicate if the measurement falls within normal limits or indicative of an elevated state based on wellrecognized body temperature ranges for the specified age of the individual being measured.

The BTS App collects the temporal artery temperature, which is processed using a polynomial function to approximate a rectal temperature. The following are the key performance specifications for the BTS App:

- Human Body Temperature Measurement Range: 94.1°F-109.4°F (34.5°C-43°C) ●
- o Laboratory Accuracy (Max): ±0.5°F (±0.3°C)

Operating Ambient Temperature:

- Temperature: 59.0°F-95°F (15°C-35°C)
- Humidity: Humidity Per ASTM E1965-98, up to 95% non-condensing ●
- Display Resolution: 0.1℃ / 0.1°F ●
- Temperature Scales: Degrees °C / °F ●
- Storage Conditions (temperature/humidity): -20°C 40°C (-4°F 113°F); Humidity ● up to 95% non-condensing
- Display Modes: Displayed temperature is the temperature of the temporal artery plus a mathematical adjustment to approximate rectal temperature.

The changes subject to this special 510k are the pre-measurement checks and values that are replaced by binary flags to ensure a body temperature measurement is only enabled when the appropriate conditions are met. These flags are:

- 1. Sensor too warm flag
- 2. Sensor too cold flag
- 3. Difference too high flaq
- 4. Skin too warm flag
- 5. Skin too cold flag

Additionally, the range for the sensor too warm/too cold flag is hardware dependent and no longer a set value.

## Comparison of Technological Characteristics:

A summary of substantial equivalence between the subject device and predicate device included in the scope of this Special 510(k) is included in the table below.

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## Table 1: Summary of Substantial Equivalence

| | Subject Device<br>Body Temperature Software | Predicate Device<br>Body Temperature Software<br>(DEN230050) | Equivalence Discussion |
|----------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Indications for<br>use | The Body Temperature Software<br>(BTS) App is a software-only mobile<br>medical application intended for over-<br>the-counter (OTC) use with<br>compatible mobile computing<br>platforms that includes a general<br>purpose infrared sensor for the<br>intermittent determination of human<br>body temperature on people of all<br>ages. | The Body Temperature Software<br>(BTS) App is a software-only mobile<br>medical application intended for over-<br>the-counter (OTC) use with compatible<br>mobile computing platforms that<br>includes a general purpose infrared<br>sensor for the intermittent<br>determination of human body<br>temperature on people of all ages. | Same |
| Intended User | The BTS App is intended to be<br>operated by users above 18 years of<br>age. | The BTS App is intended to be<br>operated by users above 18 years of<br>age. | Same |
| Device<br>Classification | Class II | Class II | Same |
| FDA Product<br>Code and<br>Regulatory<br>Classification | QZA - 21 CFR 880.2915<br>Body temperature sensing software | QZA - 21 CFR 880.2915<br>Body temperature sensing software | Same |
| Patient<br>Population | General population excluding<br>premature/preterm infants | General population excluding<br>premature/preterm infants | Same |
| Prescription | OTC | OTC | Same |
| or OTC | | | |
| Anatomical<br>Site | Forehead using a compatible<br>consumer smartphone with IR<br>sensors. | Forehead using a compatible<br>consumer smartphone with IR sensors. | Same |
| Use<br>Environment | Home/General Use | Home/General Use | Same |
| Compatible<br>devices | Pixel 8 Pro and other consumer Pixel<br>smartphone devices deemed<br>compatible with Android 14 operating<br>system release or higher | Pixel 8 Pro with Android 14 operating<br>system release or higher | Different<br>The BTS App is deemed<br>compatible with additional<br>hardware platforms that meet the<br>pre-specified requirements. This<br>addition is to include additional<br>consumer Pixel smartphones<br>as compatible devices and<br>does not raise new questions of<br>safety and effectiveness. |
| Inputs to BTS | 1. Range flag and IR sensor check<br>2. A temperature signal that qualified<br>smartphone devices generate.<br>a. The Sensor Ambient<br>Temperature is set to<br>Hardware specific<br>ranges.<br>b. Skin too warm/cold<br>checks are binary<br>flags.<br>c. Window temperature<br>difference too high<br>check is a binary flag. | 1. Range flag and IR sensor check<br>2. A temperature signal that qualified<br>smartphone devices generate.<br>a. The Sensor Ambient<br>Temperature parameter<br>is set at 15°C to 35°C | Different<br>The subject device uses binary<br>flags to check for suitable pre-<br>measurement phone hardware<br>conditions. These functions occur<br>outside the SaMD and are<br>maintained in a hardware<br>specification table.<br>The Sensor Ambient<br>Temperature is set to Hardware |
| | | | specific ranges with the subject<br>device instead of a defined range.<br>Validated laboratory accuracy<br>testing for the sensor ambient<br>temperature range supports the<br>change not raising new questions<br>of safety and effectiveness.<br><br>The skin too warm/cold and<br>the difference too high flags<br>have been modified to be<br>binary flags instead of<br>specified ranges. This<br>difference is evaluated using<br>software verification and does<br>not raise new questions of<br>safety and effectiveness. |
| Principle of<br>operation | A user's temperature is measured<br>when a forehead measurement<br>sweep is performed with the infrared<br>sensor and the signal input data is<br>provided by the platform to the BTS<br>App algorithm.<br>The BTS App performs a series of<br>checks prior to launching, during the<br>sweep and during the processing of<br>the signal to ensure that the<br>temperature data collected is valid for<br>processing. Using this valid collected | A user's temperature is measured<br>when a forehead measurement sweep<br>is performed with the infrared sensor<br>and the signal input data is provided by<br>the platform to the BTS App algorithm.<br>The BTS App performs a series of<br>checks prior to launching, during the<br>sweep and during the processing of<br>the signal to ensure that the<br>temperature data collected is valid for<br>processing. Using this valid collected<br>data, the BTS App algorithm | Same |
| | data, the BTS App algorithm<br>processes the sensor data collected<br>during the sweep and determines the<br>body temperature.<br>The displayed temperature is that of<br>the temporal artery which is<br>processed using a polynomial<br>function to approximate a rectal<br>temperature. | processes the sensor data collected<br>during the sweep and determines the<br>body temperature.<br>The displayed temperature is that of<br>the temporal artery which is processed<br>using a polynomial function to<br>approximate a rectal temperature. | |
| Specifications | | | |
| Human body<br>temperature<br>Measurement<br>Range<br>(Min/Max<br>Accuracy) | 94.1°F-109.4°F (34.5°C-43.0°C) | 94.1°F-109.4°F (34.5°C-43.0°C) | Same |
| Laboratory<br>Accuracy (Max) | ±0.5°F (±0.3°C) | ±0.5°F (±0.3°C) | Same |
| Measurement<br>Site | Temporal Artery | Temporal Artery | Same |
| Reference Body Rectal<br>Site | Rectal | Rectal | Same |
| Human body<br>temperature<br>Measurement<br>Range<br>(Min/Max<br>Accuracy) | 94.1°F-109.4°F (34.5°C-43.0°C) | 94.1°F-109.4°F (34.5°C-43.0°C) | Same |
| Operating Ambient Ranges | | | |
| Temperature | 59.0°F-95.0°F (15.0°C-35.0°C) | 59.0°F-95.0°F (15.0°C-35.0°C) | Same |
| Display<br>Resolution | 0.1°F/0.1°C | 0.1°F/0.1°C | Same |
| Temperature<br>Scales | Degrees °F/°C | Degrees °F/°C | Same |

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## Summary of Non-Clinical Testing:

The intended use of the subject device and predicate are identical, and their technological characteristics are similar. The subject device is a modification of the predicate device and utilizes the same design and operating principles. The device modifications have been verified and do not raise any new or different questions of safety and effectiveness.

The device demonstrated a laboratory accuracy of ±0.3°C per ISO 80601-2-56. Risk management was conducted in accordance with ISO 14971.

The following testing was conducted to demonstrate that the modifications to the subject device are as safe and effective as the predicate.

- Validation Testing .
Results of these tests demonstrate that the functionality, safety, and effectiveness of the subject device are adequate for their intended use, indications for use and support a determination of substantial equivalence.

## Summary of Clinical Testing:

Clinical testing was not required for this Special 510(k).

## Conclusion:

The proposed modifications to the subject device do not alter the indications for use, intended use, user interface or its core algorithm. There are no differences in the indications for use and intended use between the subject and predicate devices.

One of the technological differences is that pre-measurement checks related to 'Sensor Ambient Temperature', 'Skin temperature', and 'Sensor Window Temperature' values are replaced by binary flags that function similarly to proximity flag check in that a body temperature measurement is only enabled when the appropriate conditions are met. Additionally, the Sensor Ambient Temperature range is being set to hardware specific range instead of a predefined range.

Laboratory accuracy testing and software verification show that the modifications to the software do not raise new or different questions of safety and effectiveness and the device demonstrates substantial equivalence to the predicate device.

The subject device is substantially equivalent to the predicate device, Body Temperature Software (BTS), DEN230050.