Empower accurate core body temperature monitoring in wearables
Non-invasive, continuous, and precise measurement for healthcare, fitness, and everyday well-being.
Track Core Body Temperature in your wearable
Precise body core temperature monitoring is an established method in the medical field to give vital knowledge of the well-being of patients. In a broader field of application, the precise monitoring of body core temperature can provide vital information e.g. in healthcare applications or for athlets, military personals and industrial workers. Conventional known methods to estimate body core temperature, includes rectal or esophogal probes and ingestibale pills. These methods are inconvenient for continuous monitoring because of their unpleasant invasiness and therefore rarely used many potential applications. For this reason, varmo has developed printed, thin, and shape-conformable heat-flux sensors that when paired with a precise temperature sensor facilitates real-time, non-invasive body core temperature monitoring.
Our sensor offers a superior alternative to the traditional methods by assimilating with different areas of the skin, eliminating discomfort. The highly customizable shape and thin profile (<200 µm) enables seamless integration of the sensors with different wearables such as smart watches and health bands.
Why Core Body Temperature Matters
Early Fever & Infection Detection: A slight elevation in CBT can be a first sign of infection or inflammatory processes.
Optimized Performance in Sports: Monitoring CBT helps athletes balance exertion, hydration, and recovery—especially in hot or humid conditions.
Sleep & Circadian Insights: Fluctuations in CBT are closely linked to circadian rhythms. Tracking these changes sheds light on quality of rest and overall wellness.
Women’s Health & Fertility: Small temperature shifts can indicate ovulation windows, helping those aiming to conceive or track their cycles.
Patient Monitoring & Safety: Continuous CBT data supports clinical decision-making for acute care, long-term monitoring, and managing high-risk groups during heat waves or strenuous tasks.
How Our Sensor Technology Works
Printed Thermoelectric Heat Flux Sensor
The heat flux sensors comprises of several printed thermocouples on a flexible substrate, electrically connected in series and thermally in parallel via silver electrode. Additionally, a dielectric is printed as a filler materials between the n- and p-type legs. The key components of a heat-flux sensor are as follows:
- Thermoelectric material: Printed thermoelectric materials (Patented)
- Flexible substrate
- Encapsulation layer
Working principle on core body temperature
The estimation of body core temperature is done based on the heat flux (the rate of heat transfer) out of the skin. A prominent equation in this field is the Pennes bioheat equation [ ], which includes parameters for the heat capacity, conduction and density of tissue and blood, blood perfusion rate and metabolic heat production. However, this complex equation can be solved with a relatively simple 1D-Fourier heat equation to give a precise value of the Core body temperature (Tcbt ), when the amount of heat flux (q), the skin temperature (Tskin) and the heat transfer coefficient (U) of the specific body region the system is attached to is known:
Tcbt = q / U + Tskin
The specific heat transfer coefficient requires a calibration step, either indirectly via physical biomedical markers (e.g. height, weight, body region, …) of the person or to achieve the highest precision, the U-value can be calibrated directly with a reference measurement.
Ready to Learn More?
Curious how our sensor could elevate your wearable or research project? Dive into the data sheet for in-depth technical details, request sample units to get hands-on experience, or schedule a call with our experts to discuss how we can tailor the solution to your needs. Let’s shape the future of thermal insights together!
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