The next breakthrough in health monitoring? Ultra-precise temperature sensing technology

Why are emerging personal health monitoring technologies becoming increasingly popular in medical scenarios and daily life? To accurately answer this critical question, we first need to understand three global trends:

● Today, almost everyone has a smartphone, which is equivalent to carrying a high-performance computer, a smart medical sensor center that operates 24/7, and a display screen.

● The population of developed industrial countries is aging rapidly, and the incidence of diseases among the elderly is higher. At the same time, young people are more concerned than in the past about how to extend their healthy lifespan. These groups and the healthcare providers who serve them can use new technologies to optimize their lifestyles and regulate key factors such as exercise, diet, sleep, and stress to help them make healthier life choices.

● As predicted by Moore's Law, semiconductor technology continues to advance, making electronic devices used for computing and sensing smaller, more powerful, lower cost, and lower power consumption. This means that medical sensors that were once only available in expensive medical equipment can now be integrated into affordable portable or wearable devices.

These trends are blurring the lines between medical devices and consumer devices. Today, even individual users can monitor key indicators of their health and lifestyle, such as blood pressure, heart rate, and sleep quality, through devices such as smart watches, activity tracking bracelets, smart rings, and even earbuds.

At the same time, medical institutions are also adopting digital medical models in hospitals and outpatient settings, which can achieve continuous and automatic monitoring of patients without the intervention of medical staff. Wearable devices such as smart skin patches and bracelets can continuously synchronize patient data to a central system, which is then monitored by artificial intelligence (AI) algorithms and other software tools. When human intervention is detected, the system will automatically notify medical experts.

Core body temperature: an important diagnostic indicator

Thanks to advances in sensor technology, consumer wearable devices have achieved near-medical-grade quality in measuring multiple vital signs, including blood pressure, heart rate, and blood oxygen saturation.

However, the information provided by core body temperature as a vital sign is also critical or even indispensable for certain diagnostic and monitoring purposes. For example, core body temperature is an accurate indicator of the state of a woman's fertility cycle, stress levels, and sleep quality. It could also provide potentially life-saving early warning signs of a fever or sepsis.

Outside of the medical field, core body temperature monitoring is also used to optimize the training of endurance athletes, helping them improve their training results and avoid excessive physical fatigue.

A previously little-known product in ams’ OSRAM sensor portfolio is now becoming a hot topic in the industry and is rapidly gaining market share, enabling a new generation of consumer and medical wearable devices to measure core body temperature.

For example, the AS6221 digital temperature sensor is the result of decades of expertise and intellectual property in the design and manufacture of ultra-precise mixed-signal semiconductors. With amsOSRAM’s unique technology, this temperature sensor meets the needs of manufacturers of new core body temperature monitoring equipment: compared with similar products, the AS6221 is more accurate, smaller and more power-efficient, making it the "unsung hero" that pushes personal health monitoring technology to new heights.

AS6221: Optimized for body temperature measurement

The advantage of advanced temperature measurement technology is its accuracy. The AS6221 has an impressive maximum measurement error of ±0.3°C over its operating range of -40°C to 125°C. However, what makes it unique is that the measurement accuracy has been optimized specifically for medical applications: the normal human body temperature is approximately 37°C, so the measurement accuracy is optimized in the range of -25°C to 55°C, with a maximum error of ±0.10°C, and in the range of 20°C to 42°C, the error is only ±0.09°C.

Such high accuracy is critical to the development of a new generation of core body temperature monitoring systems, such as our partner greenteg's CALERA® sensor technology. Traditionally, measuring core body temperature usually requires inserting an invasive probe or swallowing an expensive electronic pill. The working principle of this product is not to measure core body temperature directly, but to calculate the core body temperature value from the heat flux on the skin surface through a complex algorithm.

There is some inherent error in converting a direct measurement of skin temperature to an indirect calculation of core body temperature. And any errors in skin temperature measurement will be amplified when converted to core body temperature.

Therefore, products that incorporate technology such as CALERA® sensors must be as accurate as possible when measuring skin temperature. This is where the AS6221 temperature sensor's ±0.09°C maximum error comes into play. Size is also an important factor; components must be suitable for use in skin patches and other portable devices.

The ams-OSRAM Vital Signs Monitor (VSM) reference design integrates greenteg’s CALERA® sensor technology on the athlete’s wrist

Ultra-precise temperature measurement technology for multiple applications

This example shows that temperature measurement plays a key role in both professional and consumer medical monitoring devices, as well as sports equipment that helps endurance athletes optimize their training, but its uses go far beyond that.

For example, the safety equipment worn by firefighters needs to be able to monitor body temperature and issue an alarm when the firefighter is in danger of overheating. In the world's hottest regions, such as the Middle East, hyperthermia, the danger of overheating, is a serious risk. Today, as the global climate crisis causes average temperatures to rise, this risk is increasing. Combining a smartwatch or bracelet with an app can provide a reliable risk solution: when the wearer is in danger, the software can promptly alert emergency services or their loved ones.

Accurate temperature measurements can also play a key role in other medical applications. For example, enzymes that measure blood sugar levels through a skin patch require accurate temperature data to calibrate the sensor's measurement output in real time. Temperature sensors can also be used in dialysis machines, blood transfusion equipment or insulin pumps to ensure that blood or insulin is heated to the patient's body temperature before being injected into a vein.

In these and many other application scenarios, extremely high measurement accuracy is of great value - especially in the human body temperature range, where precise measurement technology is becoming a focus.