From motivational underwear to sweat health analysis, the wearable industry lacks only imagination

Recently, there has been a lot of news related to "skin". First, the Nanoelectronic Device Laboratory of the Swiss Federal Institute of Technology in Lausanne (EPFL) announced the development of a nanoscale transistor sensor that can scan liquids (such as sweat) in real time, providing real-time and accurate detection of personal hydration, stress or fatigue levels.

Soon after, the Institute for Basic Science (IBS) and Seoul National University in South Korea developed an ultra-thin wearable quantum dot light-emitting diode (QLED) that can be attached to human skin like a sticker, opening up other new application possibilities for wearable electronic products that integrate high-resolution full-color displays.

More interestingly, a Japanese company has invented a talking bra that delivers positive messages to female users. According to the manufacturer, the bra is equipped with sensors that can detect tension or increased pulse in a woman's voice, and thus deliver comforting messages to the wearer to relieve stress and anxiety: for example, encouraging words such as "If you give it your all, you'll be fine!" or when the wearer asks, "Do I look beautiful?", the answer is "Very beautiful" or "Simply stunning." In addition, the bra can also connect to a smartphone to help the wearer record how many steps they have walked, how far they have traveled, and how many calories they have burned.

David Andeen, reference design director at Maxim Integrated, said in an interview with EE Times: “Skin conductivity (GSR) measurement is a daunting challenge. First, there is no absolute reference number in GSR. You can’t find a similar reference point like you can for temperature measurement. Second, GSR can be generated by a range of excitation signal frequencies, so signal integrity is critical to ensure valid measurements. Third, GSR measurements vary with changes in the spacing between skin electrodes.”

In simple terms, GSR measurements can be thought of as resistance measurements with complex components, measuring information such as the amount of sweat, relative hydration, and adrenal response of the body. In medical and health applications, GSR is particularly valuable for slow movements such as yoga, where heart rate monitors and accelerometers produce lower data, but the body still uses a lot of force.

"To be honest, wearable applications are still in the early stages of development, and GSR is not being incorporated as quickly as motion and heart rate sensors," said David Andeen, but he believes that GSR's application potential is unquestionable. "There are many occasions where GSR may be used. In the past, GSR was often used for applications such as monitoring emotions and lie detectors, but if GSR can be combined with other data (such as accelerometers and heart rate), coupled with cloud computing and a large number of data points, GSR can be used to analyze the causes and conditions that affect health."

MAXREFDES73# is the industry's first GSR reference design launched by Maxim Integrated. It integrates a digital-to-analog converter (DAC) and an analog-to-digital converter (ADC), as well as a microcontroller with advanced power management functions, and provides firmware and an easy-to-use Android app, which effectively saves development and testing time for wearable products and helps users quickly bring mobile medical/health products to market. MAXREFDES73# uses a wristband package and includes body temperature readings, Bluetooth communication, and a rechargeable battery (a single battery can be powered for up to one week).

“When designing this system, we focused on developing a platform that allows customers to focus on how to use GSR. We completed the hardware circuit design and provided excellent signal integrity, while giving customers great flexibility to generate their own data and draw their own conclusions on how to apply GSR,” said David Andeen. “An added benefit of the MAXREFDES73# is that the platform is also being used by data scientists and algorithm developers, who can move directly to prototyping without any additional preparation.”

Click " Read More " to learn more about the MAXREFDES73# reference design and get free online access to hardware and firmware design files and test data.