Silicon Labs has introduced a family of optical biometric sensors providing advanced heart rate monitoring (HRM) by transcutaneous optical measurements, along with electrocardiogram (ECG) capabilities, for a range of wearable fitness and wellness products.
Si117x sensor modules combine ultra-low power, high sensitivity and integration, for smart watches and wrist-based, patch-type and other wearables requiring long battery life and enhanced HRM accuracy. To simplify development and speed time to market, Silicon Labs offers a complete, end-to-end sensing solution featuring the Si117x sensor module, HRM algorithm, Wireless Gecko SoCs for Bluetooth connectivity, and a wrist-based development kit with sample code and example projects.
Biosensors with ECG function for heart rate monitoring in wearables – [Link]
Engineers and scientists from the UCLA Henry Samueli School of Engineering and Applied Science and SRI International, California, have created a thin flexible device that could keep smartphones and laptop computers cool and prevent overheating. The component is based on the electrocaloric effect – a phenomenon where the temperature of material changes when an electric field is applied to it. The research has been published in Science.
The system’s flexibility also allows it to be used in wearable electronics, robotic systems, and new types of personalized cooling systems. It is the first demonstration of a solid-state cooling device based on the electrocaloric effect. The method devised by UCLA and SRI researchers is very energy-efficient. It uses a thin polymer film that transfers heat from the heat source – a battery or a processor – to a heat sink, and alternates contact between the two by switching on and off the electric voltage.
Because the polymer film is very flexible, the system can be used in devices with complex shapes or moving surfaces. Body tracking wearable devices can easily accommodate this flexible cooling device. Such cooling pad could keep a person comfortable in a hot office and thus lower the electricity consumption for air conditioning. Or it could be placed in a shoe to keep a runner comfortable while running in the sun. It’s like a personal air conditioner.
The tendency of flexible electronics to overheat remains a major challenge for engineers. The cooling systems in larger devices like air conditioners and refrigerators, which use vapor compression, are just too large for mobile electronics. The new cooling device produces a specific cooling power of 2.8 watts per gram and a COP of 13. This is more efficient and compact than the existing surface-mountable solid-state cooling technologies, opening a path to using the technology for a variety of practical applications.
Roy Kornbluh, an SRI research engineer, said,
The development of practical efficient cooling systems that do not use chemical coolants that are potent greenhouse gases is becoming even more important as developing nations increase their use of air conditioning.
Wearable electronic devices that intend to track and measure the body’s movements must be soft enough to flex and stretch to accommodate every body-movement. But, integrating rigid electronics on skin-like flexible materials has proven to be challenging. Clearly, Such components cannot stretch like soft materials can, and this mismatch frequently causes wearable devices to fail. Recently scientists solved this problem by developing a new method called hybrid 3D printing.
A collaboration between the Wyss Institute, Harvard’s John A. Paulson School of Engineeringand Applied Sciences, and the Air Force Research Laboratory, has resulted in developing hybrid 3D printing method. It combines soft, electrically conductive inks, and matrix materials with rigid electronics into a uniformly stretchable device. Alex Valentine, a Staff Engineer at the Wyss Institute says,
With this technique, we can print the electronic sensor directly onto the material, digitally pick-and-place electronic components, and print the conductive interconnects that complete the electronic circuitry required to ‘read’ the sensor’s data signal in one fell swoop.
To make the circuits and the flexible layers, the researchers use thermoplastic polyurethane (TPU), both pure and with silver flakes. The method is quite easy to understand. As both the substrate and the electrodes contain TPU, they firmly adhere to one another while they are co-printed layer-by-layer. After the solvent evaporates completely, both of the inks harden, forming an integrated system that is both flexible and stretchable.
As the ink and substrate are 3D-printed, the scientists have complete control over where and how the conductive features are patterned. Thus they can design circuits to create soft electronic devices of nearly every size and shape. The hybrid 3D printing method enables development of flexible, durable wearable devices that move with the body.
Conductive materials exhibit changes in their electrical conductivity when stretched. Soft sensors, that detect movements, are made of those materials and are coupled with a programmable microcontroller to process those data. The microcontroller also transmits the data to communicate in a human-understandable way. As a proof-of-concept, the team created two devices – a wearable device that indicates how much the wearer’s arm is bending and a pressure sensor in the shape of a person’s left foot.
A smartwatch with fall and location detection, reminders and more, designed to help you or your loved one with Alzheimer’s!
When I saw Infineon’s Sensor Hub Nano, it appeared to be a good candidate in such a project, because of its very small size and BLE capabilities. With the accurate pressure sensing, it could be used to detect if the patient has fallen and also tell where exactly the patient is in the house.
The nRF52840 SoC of Nordic Semiconductor is based on a 32-bit ARM Cortex-M4F CPU running at 64 MHz with flash and RAM integrated on chip. Ultra low-power wireless applications can use this advanced multi-protocol SoC with different communication protocols. The 2.4 GHz transceiver supports Bluetooth low energy (Bluetooth 5), 802.15.4, ANT and proprietary protocols. The transceiver also supports high resolution RSSI measurement and automated processes to reduce CPU load. Moreover, EasyDMA for direct data memory access and packet assembly provides full support for hardware (figure 1). The device maintains the compatibility with existing products such as nRF52, nRF51 and nRF24 series.
Bluetooth 5 and SoC
Bluetooth 5 (500kbs e 125kbs) is the latest version of the well-known wireless technology. It increases the range of four times and the throughput of eight times, making this technology much more suitable for ultra low-power wireless applications such as wearable, Smart Home and more generally for Internet-related applications (IoT, IIoT). The ultra low power consumption of the Bluetooth 5 protocol facilitates high performance, advertising extension and modulation schemes.
nRF52840 SoC uses power management resources to maximize job processes and achieve an optimal energy efficiency. The power supply ranges between 1.7V and 5.5V ensures a wide choice of batteries. In addition, SoC can also work with USB direct power supply without external regulators. Especially relevant, all devices have automatic clock management with adaptive features to maintain minimal power consumption.
32-bit ARM Cortex-M4F Processor
1.7v to 5.5v operation
1MB flash + 256kB RAM
Bluetooth 5 support for long range and high throughput
802.15.4 radio support
PPI –Programmable Peripheral Interconnect
Automated power management system with automatic power management of each peripheral
Configurable I/O mapping for analog and digital I/O
48 x GPIO
1 x QSPI
4 x Master/Slave SPI
2 x Two-wire interface (I²C)
2 x UART
4 x PWM
USB 2.0 controller
ARM TrustZone CryptoCell-310 Cryptographic and security module
AES 128-bit ECB/CCM/AAR hardware accelerator
Digital microphone interface (PDM)
Low power comparator
On-chip 50Ω balun
On-air compatible with nRF52, nRF51 and nRF24 Series
The NRF52840-PDK is a versatile development kit based on nRF52840 SoC for the development of projects by using Bluetooth Low Energy, ANT, 802.15.4, and proprietary 2.4GHz protocols. Moreover, It is also hardware-compatible with the Arduino Uno R3 standard, allowing to use third-party compatible shields. Adding an NFC antenna, the kit enables the NFC tag feature (figure 2 and 3).
Valencell, a biometric wearable sensor technology company, in partnership with STMicroelectronics, an electronics and semiconductor manufacturer, announced a new highly accurate and scalable development kit for biometric wearables. The kit combines ST’s compact SensorTile turnkey multi-sensor module with Valencell’s Benchmark biometric sensor system.
The SensorTile is a tiny IoT module (13.5mm x 13.5mm) that features a powerful STM32L4 microcontroller, a Bluetooth Low Energy (BLE) chipset, a wide spectrum of high-accuracy motion and environmental MEMS sensors (accelerometer, gyroscope, magnetometer, pressure, temperature sensor), and a digital MEMS microphone.
The on-board low-power STM32L4 microcontroller makes it work as a sensing and connectivity hub for developing firmware and shipping in products such as wearables, gaming accessories, and smart-home or IoT devices.
FCC (ID: S9NSTILE01) and IC (IC: 8976C-STILE01) certified
Included in the development kit package:
SensorTile expansion Cradle board equipped with audio DAC, USB port, STM32 Nucleo, Arduino UNO R3 and SWD connector
SensorTile Cradle with battery charger, humidity and temperature sensor, SD memory card slot, USB port and breakaway SWD connector
100 mAh Li-Ion battery
Plastic box for housing the SensorTile cradle and the battery
SWD programming cable
Software libraries and tools
STSW-STLKT01: SensorTile firmware package that supports sensors raw data streaming via USB, data logging on SDCard, audio acquisition and audio streaming. It includes low level drivers for all the on-board devices
BLUEMICROSYSTEM1 and BLUEMICROSYSTEM2: STM32Cube expansion software package, supporting different algorithms tailored to the on-board sensors
FP-SNS-ALLMEMS1 and FP-SNS-MOTENV1: STM32 ODE functional packs
ST BlueMS: iOS and Android demo Apps
BlueST-SDK: iOS and Android Software Development Kit
Compatible with STM32 ecosystem through STM32Cube support
“Valencell’s Benchmark solution leverages the high accuracy of ST’s MEMS sensor technology along with SensorTile’s miniature form factor, flexibility, and STM32 Open Development Environment-based ecosystem,” said Tony Keirouz, Vice President Marketing and Applications, Microcontrollers, Security, and Internet of Things, STMicroelectronics. “Combined, SensorTile and Benchmark enable wearable makers to quickly and easily develop the perfect product for any application that integrates highly accurate biometrics.”
Integrating ST’s SensorTile development kit with Valencell’s Benchmark sensor technology simplifies the prototyping, evaluation, and development of innovative wearable and IoT solutions. That’s done by delivering a complete Valencell PerformTek technology package, ready for immediate integration and delivery into wearable devices. The collaboration with ST expands on previous work that incorporated the company’s STM32 MCUs and sensors into Valencell’s Benchmark sensor system.
“Working with ST has allowed us to bring together the best of all sensors required to support the most advanced wearable use cases through our groundbreaking Benchmark sensor system,” said Dr. Steven LeBoeuf, president and co-founder of Valencell.
The kit is in volume production and is available for about $80. You can order it and get more information and technical details through the official page.
A scalable development kit integrates ST SensorTile with Valencell’s Benchmark biometric sensor system to accelerate smart wearable and IoT product development. By Graham Prophet @ edn-europe.com
Valencell (Raleigh, North Carolina) is a company active in high-performance biometric data sensor technology; in a joint announcement with STMicroelectronics the two companies have disclosed an accurate and scalable development kit for biometric wearables that includes ST’s compact SensorTile turnkey multi-sensor module integrated with Valencell’s Benchmark biometric sensor system. Together, SensorTile and Benchmark comprise the most useful portfolio of sensors to support the most advanced wearable use cases, according to their designers.
Biometric sensor platform for wearables and IoT – [Link]
Everlight (New Taipei City, Taiwan) has introduced an ambient light sensor that operates at 550nm with a very low signal calculation failure rate and a high current efficiency. An anticipated application for this device is heart rate signal detection in wearable electronics for the health and fitness sector. by Graham Prophet @ edn-europe.com:
Based on the principle of PPG (photoplethysmogram), the heart rate signal is calculated according to the current changes in transmission and reflection between a green light LED and the sensor to detect the systolic and diastolic blood vessel rythym. With a large detection area of 8.1mm ², improved signal strength is available from the ALS-PD50-42C. The larger sensing area can also improve the capabilities in instances when there are signal interferences caused by people’s skin colour, tattoos and hair on the skin.
Ambient light sensor for heart rate sensing in wearables – [Link]
Biosensors for consumer wearable devices is a new trend as it facilitates multiplexed physiological monitoring for quantitative assessment of body functions. Highly functional wearable biosensors that can also provide meaningful diagnostics to guide therapeutics would be extremely valuable to end-user consumers or health-professionals.
Researchers at The University of Texas at Dallas developed a wearable device that is lancet-free, label-free diagnostic sensor which can monitor an individual’s glucose level via perspiration on the skin. They worked with sweat, not any other fluids like urine or tears, since sweat is the most widely evaluated body fluid as it contains a lot of medical information and is relatively easier to stimulate, gather, and analyze. To increase the usability of the sensor, researchers had also tested the combined detection of stress biomarker cortisol in human perspiration using the same sensor platform
In order to make wearable biosensors as successful consumer products it is important to demonstrate enhanced multiplexed functionality, reliability, and ease-of-use through non-invasive (without skin break) monitoring of body fluids. Thus, researchers designed and fabricated 3-D nanostructured semiconducting ZnO sensing elements to establish optimal electron transfer efficacy between 4 immobilized glucose and cortisol molecules and the electrode surfaces. ZnO has been successfully used as electrode material for enzyme immobilization and glucose detection.
“In our sensor mechanism, we use the same chemistry and enzymatic reaction that are incorporated into blood glucose testing strips. But in our design, we had to account for the low volume of ambient sweat that would be present in areas such as under a watch or wrist device, or under a patch that lies next to the skin.” said Prasad, The Cecil H. and Ida Green Professor in Systems Biology Science.
Their design works with volumes of sweat less than a microliter, which is the approximate amount of liquid that would fit in a cube the size of a salt crystal. The system also provides a real-time response in the form of a digital readout.
Glucose monitoring has tremendous importance in the field of diabetes management and this non-invasive detection techniques based on body fluids are pain free, comfortable and offer patient adaptability. However, sweat glucose concentrations have a time lag and concentration range varies with respect to blood glucose concentrations due to the diffusion barriers in human physiology.
The research was supported by the Cecil H. and Ida Green endowed fellowship at UT Dallas.
Heart rate monitoring is a common procedure for most of health related projects. Therefore, producing sensors modules and circuit boards for such tasks will facilitate and push forward the development of new health-tech projects.
Maxim Integrated, an analog and mixed-signal integrated circuits manufacturer, has developed a new module for measuring heart rate and pulse oximetry. It’s called “MAXREFDES117#”, derived from Maxim Reference Design, and it is a small board which is compatible with Arduino and Mbed boards, enabling a wide range of possibilities for developers.
MAXREFDES117# can be powered by 2 to 5.5 volts. It is a photoplethysmography (PPG)-based system that uses optical method for detecting heart rate and SpO2. It consists of three main parts:
1. MAX30102, a high sensitivity heart rate and pulse oximetry sensor. It is used with integrated red and IR LEDs for heart rate and pulse oximetry monitoring.
2. MAX1921, a low-power step-down digital-to-digital converter. It generates 1.8 V from input to supply the sensor.
3. MAX14595, a high speed logic-level translator. It works as an interface between the sensor and the connected developing board.
The board size is only 0.5” x 0.5” (12.7mm x 12.7mm) and has low power consumption that make it suitable for wearable applications. Thus, it can be placed on a finger, an earlobe, or other fleshy extremity.
Accuracy of data collected by MAXREFDES117# depends on the used platform. According to the results with tested boards, Arduino boards give less accuracy than mbed ones because of theirs smaller SRAM size.
MAXREFDES117# is available for $20, it can be ordered online through the website.
More detailed information and quick start guide are presented here. In addition, all of the source files including schematic, PCB, BOM, and firmware are open and can be reached at the official product page.