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Body temperature measurement is an important tool that can assist in the early diagnosis of infectious or other disease. Just like any other thermometry method, ensuring on-going, reliable clinical temperature measurement requires the periodic calibration of the clinical thermometer (and its calibrator) by an accredited laboratory to ensure measurement traceability.
NPL has significant leading expertise in temperature measurement and is able to offer clinical thermometer calibration and related services.
The ISO standard relating to medical electrical equipment (ISO 80601-2-56:2017) specifies temperature and humidity environments in which portable thermometers must be proven to operate. NPL can perform calibrations of clinical thermometers to meet this standard, using the combination of a calibration system traceable to national temperature standards placed inside an environmental chamber. A series of temperatures over a range of ambient temperatures (from 15 °C to 45 °C) and relative humidities (from 20 %rh to 80 %rh) can be accommodated. The time response of the device to applied heating and cooling can also be measured, in accordance with the standard.
Some examples of the services we provide are listed below. Our diverse skill set enables us to provide bespoke solutions. If you don’t see what you are looking for please contact us to discuss your specific requirements.
NPL can calibrate both clinical thermometers (e.g. oral or tympanic/ear) and manufacturer provided calibration sources and our services benefit from direct traceability to the national standards of temperature yielding very low measurement uncertainties. We provide services for temperature measurement devices which employ both contact or non-contact temperature sensor technologies.
Thermal imagers measure infra-red radiation and through that measurement, and a number of assumptions, are able to infer surface temperature. The technology is well established for qualitative applications such as target identification and recognition for defence and security and in preventative maintenance and quality assurance settings.
The application of thermal imaging technologies to quantitative applications such as healthcare, specifically its use in body temperature screening, has seen recent widespread growth. However there are a number of technical challenges which must be overcome, in order to use thermal imaging for reliable temperature measurement in clinical applications.
NPL is able to help stakeholders (including users and manufacturers of thermal imagers) to understand the capabilities and current limitations of thermal imaging systems. Our expert team can help with measurement assessment, verification, traceable calibration and the determination of measurement uncertainty associated with the data they produce. As part of our national measurement system responsibility, NPL have benchmarked a range of commercial off the shelf thermal imaging systems and the temperature group has published peer reviewed work in this field.
Examples of NPL’s work in the field of thermal imaging technology development:
We have collaborated with researchers and companies on the robust application of thermal imaging where absolute confidence in measurement is required.
In 2008 NPL’s experts were involved in creating the ISO standard for fever screening using thermal imaging and we have worked with the FDA on the assessment processes for technology assessment in this field.
NPL is helping manufacturers and users of thermal imaging technology to understand the limits and potential applications of the technology through:
Expert advice and consultancy in temperature measurement across a wide variety of settings including; academia, accredited laboratories, healthcare professionals and industry.
NPL provides training courses to improve best practice in temperature measurement and the overview of the course can be accessed here.
Whether contact or non-contact measurement of temperature is performed, all thermometers have an uncertainty associated with the measurements they perform.
The relevant ISO standard for clinical thermometry stipulates that a clinical temperature measurement device must have a measurement uncertainty associated with the device of not greater than to ± 0.3 °C (k = 2) when manufactured.
There are however, a number of other factors which over time can impact this measurement uncertainty, for example:
In addition there are other factors which contribute further to the measurement uncertainty of the clinical thermometer, some of which can be very significant:
Regular, traceable calibration of the clinical thermometer by an accredited provider combined with training programmes which ensure consistent use of the device enables users to have confidence in the temperature data required to undertake reliable triage and diagnosis decisions. Traceable accredited calibration will reliably identify any changes in the thermometer performance. We have the expertise to provide both accurate and authoritative calibration services for both contact and non-contact thermometers used for clinical temperature measurement. More details are given below.
View Dr Graham Machin’s presentation on the challenges of non-contact body temperature measurement.
Clinical Temperature Measurement Presentation
Our research and measurement solutions support innovation and product development. We work with companies to deliver business advantage and commercial success. Contact our Customer Services team on +44 20 8943 7070