STMicroelectronics (ST), the world's leading semiconductor company serving multiple electronic applications, recently launched a new biosensor chip for smart watches, sports bands, smart rings, smart glasses and other next-generation smart wearable medical devices. The ST1VAFE3BX chip integrates high-precision biometric inputs with ST's market-proven inertial sensors and AI core. Among them, the AI core performs activity detection on the chip, ensuring faster motion tracking and lower power consumption.

Simone Ferri, Vice president of ST APMS Products and general manager of MEMS Sub-Products, said: "Smart wearable electronics are a key enabling technology to increase personal health awareness and ignite a fitness craze. Today, everyone can monitor their heart rate, track their body movements and geographical location on their watch. Our latest biosensor chip can enhance the product power of wearable devices, with motion and biosignal detection capabilities, small and thin appearance, and low power consumption budget."

Analysts at Yole Development believe that the market growth of wearable monitors has the opportunity to surpass the overall health market, including consumer medical devices approved by health organizations that can be sold over the counter. By creating a complete, precise sensor input on the chip, ST's chip design experts are driving innovation in all areas, providing advanced monitoring capabilities such as heart rate variability, cognitive function and mental state.

The ST1VAFE3BX brings the opportunity for wearable applications to expand from the wrist to other locations on the body, for example, smart patches for lifestyle improvement or medical monitoring purposes. St's customers BM Innovation (BMI) and Pison are at the forefront of innovation in this area and have already used this sensor in the development of new products.

In the field of wireless sensors, BMI is an experienced electronics design contract company with an extensive portfolio of projects, including several market-leading heart rate monitoring and athlete training monitoring systems. Richard Mayerhofer, BMI Managing Director, said: "With ST's new biosensors, we are able to develop the next generation of accurate athlete performance monitoring systems, including chest strap or slip-on ECG analyzers. Integrating vAFE's analog signal with acceleration sensor motion data in a compact package allows us to combine context-aware information for accurate data analysis. Supporting AI algorithms directly on the sensor is exactly the solution we've been looking for."

David Cipoletta, CTO of Pison, an advanced technology development company focused on improving health and human potential, added: "ST's new biosensor is an excellent solution for smartwatch gesture recognition as well as cognitive performance and neural health monitoring. Leveraging this technological advancement, we have significantly enhanced the functionality and user experience of smart wearables."

The ST1VAFE3BX is now in production in a 2mm x 2mm 12-pin LGA package and can be purchased from eSTore (request free sample) and distributors.

At Electronica Munich 2024, a major trade show in Munich from November 12 to 15, visitors can see the ST1VAFE3BX at a sensing technology demonstration at the ST stand in Hall C3 101.

Technical details

The design of analog front-end circuits for biometric sensors is difficult and subject to unpredictable factors such as skin preparation before detection and the location of sensor electrodes on the body. The ST1VAFE3BX provides a fully functional vertical analog front end (vAFE) that simplifies the detection of different types of vital signs that indicate physical or emotional states.

As a result, manufacturers of health products and medical devices can expand their product offerings by adding monitoring capabilities such as electrocardiograms (ECG), electroencephalograms (EEG), seismic electrocardiograms (SCG), and electroneurograms (ENG) to their products, unlocking a new market for affordable, easy-to-use, and reliable devices that can indicate health status or physiological responses to events such as stress or excitement. In the future, there may be more wearable devices that help enhance medical and fitness functions and improve self-awareness.

In addition to integrating this precise analog front end on the chip, the ST1VAFE3BX also utilizes ST's MEMS technology capabilities to integrate an inertial sensor accelerometer on the chip. This accelerometer provides information about the wearer's movement, synchronizes the legendary data with the biometric sensing signal, and helps the application infer the connection between the actual measured signal and physical activity.

The ST1VAFE3BX also integrates ST's machine learning kernel (MLC) and finite state machine (FSM), allowing product designers to implement simple neural processing decision trees on-chip. These AI algorithms allow sensors to autonomously handle functions such as activity detection, reducing the computing load on the main CPU, speeding up system response, and minimizing power consumption. In this way, ST's sensors enable smart devices to provide more complex functions and have longer battery life, thus increasing the utility of the devices. ST also offers software tools, such as MEMS Studio in the ST Edge AI Suite, to help designers unlock maximum performance from ST1VAFE3BX, and an MLC decision tree configuration tool.

The ST1VAFE3BX biodetection signal channel includes a vAFE front end with gain settable and 12-bit ADC resolution. The maximum output data rate of 3200Hz is suitable for a variety of biopotential measurements to quantify heart, brain and muscle activity.

The product's supply voltage range is 1.62V to 3.6V, with typical operating current of only 50µA, which can be reduced to 2.2µA in energy saving mode.

The on-chip, low-noise accelerometer has a settable range from ±2g to ±16g.