Developments and solutions of consumer medical healthcare wearable devices

Modern consumer medical healthcare wearable devices are becoming increasingly affordable and are becoming mainstream. These devices incorporate advanced sensors and are battery-powered, such as over-the-counter (OTC) hearing aids and continuous glucose monitors (CGMs). Their compact size and low power consumption bring significant benefits to patients' medical care and quality of life. This document provides a brief introduction to the development of these consumer medical healthcare wearable devices and introduces onsemi's highly competitive portfolio in these fields.

Many people experience mild to moderate hearing loss caused by age, genetic factors, or prolonged exposure to loud sounds. Hearing loss negatively impacts quality of life and can lead to social isolation, depression, and cognitive decline. OTC hearing aids represent a major shift in hearing care, offering adults with mild to moderate hearing loss an affordable and accessible solution without the need for a prescription or professional fitting. They make it easier for millions of people to address hearing challenges that often go untreated for years. OTC hearing aids amplify sound to improve communication and quality of life, helping to reduce risks associated with untreated hearing loss. While OTC hearing aids provide convenience and cost savings, they are best suited for individuals who can self-manage their hearing needs and understand their limitations compared to professionally fitted devices.
 
OTC hearing aids are a rapidly evolving segment of the hearing health industry, driven by regulatory changes aimed at improving accessibility and affordability. They differ from prescription hearing aids in that they are self-fitted and generally less expensive. However, OTC hearing aids offer limited personalization and are not suitable for people with severe hearing loss.
 
The key components of a hearing aid include a digital signal processor (DSP), power management IC (PMIC), Bluetooth Low Energy (BLE) radio for control and audio streaming, microphone, and speaker. Currently, manufacturers are exploring the integration of artificial intelligence (AI) into the DSP process to assist with various tasks, such as noise analysis to improve listening comfort and speech extraction from background noise.

Diabetes is a chronic health condition that affects how the body regulates blood sugar, its primary source of energy. Normally, the hormone insulin helps glucose enter cells for energy, but in diabetes, the body either does not produce enough insulin or cannot use it effectively. This leads to elevated blood sugar levels, which, if left untreated, can cause serious health complications or even death. Continuous glucose monitors (CGMs) are sensor-based wearable blood glucose monitoring devices inserted under the skin, providing continuous glucose readings which can be monitored remotely. These devices allow users to know their glucose levels in real time, enabling easier disease management.
 
CGM devices have rapidly emerged as a cornerstone of diabetes management, especially for consumer use. These wearable sensors track blood glucose in real-time, empowering individuals to manage diabetes with non-invasive glucose monitoring without finger pokes, and enabling remote monitoring by healthcare providers. The sensor is inserted under the skin where it measures glucose in interstitial fluid. The device also contains a transmitter to send the readings wirelessly. The devices must be replaced approximately every two weeks to prevent allergic reactions and due to battery constraints.
 
The CGM's electrochemical sensor has three electrodes: a working electrode (WE) where the glucose oxidation current is generated, a counter electrode (CE) that balances the reaction, and a reference electrode (RE) that provides a stable voltage reference for accurate measurement. The tiny current from the WE is converted to a voltage and processed digitally. With additional digital processing and wireless communication, it is possible to build powerful connected solutions that can provide insight into the environment around us as well as our own bodies.

onsemi offers a wide range of solutions for consumer medical healthcare wearable devices. Due to space constraints, this document will focus on the following key products: the Analog Front-End (CEM102), the Bluetooth Low Energy (RSL15), and the Battery Charge Controller (HPM10).
 
The CEM102 is an analog front-end (AFE) IC specifically developed for electrochemical sensors in continuous glucose monitoring (CGM) and similar low-current sensing applications. It bridges the sensor interface to the digital processing domain and employs amperometric measurements for very low currents. With its small form factor and low power consumption, it enables further miniaturization and extended battery life for many end applications.
 
The CEM102 is designed to be used together with onsemi's RSL15, bringing several additional system-level benefits such as optimized system power consumption and supply voltage. This includes operating the system across a wide 1.3 to 3.6 V supply voltage range, typically using a single 1.5 V silver oxide battery or a 3 V coin cell.
 
The CEM102 creates a bridge from the sensor network to digital processing and features sensor conditioning capabilities to support accurate measurements. It offers flexible configuration supporting 1 to 4 electrodes, independent bias voltage for dual working electrodes, extensive diagnostic capabilities, and extremely low system current consumption of 3.5 µA for longer battery life. It can also monitor ADC output for threshold violations to detect abnormal sensor conditions, and is available in a small form factor WLCSP25 package.
 
To accelerate product development, onsemi has developed the CEM102-EVB evaluation board, which includes the CEM102 chip along with the RSL15 chip and sample code for setting up and performing measurements with the CEM102. This facilitates a jump start of system and firmware development.

Bluetooth Low Energy (BLE) is a wireless technology designed for short-distance communication with significantly lower power consumption than classic Bluetooth. It is ideal for devices that need to send small amounts of data, allowing them to run for months or even years on a small coin-cell battery. BLE is aimed at applications in healthcare, fitness, IoT, and more.
 
The BLE radio is designed for ultra-low power operation, enabling battery-powered devices to last for several years. It is cost-effective and suitable for a wide range of applications. It is optimized for small data transfers rather than large streams like audio, and maintains a similar communication range to classic Bluetooth despite its lower power profile.
 
onsemi's RSL15 is an ultra-low power Bluetooth® Low Energy 5.2 wireless microcontroller (MCU) built around an Arm® Cortex®-M33 processor, ideal for battery-powered sensing applications like medical healthcare wearables. It offers exceptional design flexibility for high-performance, ultra-low-power applications through integrated power management, flexible GPIO and clocking schemes, and a wide supply voltage range. With industry-leading energy efficiency, the RSL15 minimizes battery drain, enabling smaller batteries and longer life for battery-powered sensors. It is recognized as the industry's lowest-power flash-based secure Bluetooth® Low Energy MCU and comes with an easy-to-use SDK for streamlined development.
 
The RSL15 supports a higher temperature range (-40 to +85°C). This industry-leading ultra-low-power MCU comes with an easy-to-use SDK and achieves top scores in ULPMark - CoreMark, making it the most efficient MCU in active processing. It features ultra-low power operation with sleep mode wakeup (3V V_BAT) at 36nA, deep sleep mode with IO wake-up at 25-57 nA, Rx sensitivity (Bluetooth® Low Energy mode, 1 Mbps) of -9dBm, data rates from 62.5 to 2000 kbps, and transmitting power from -17 to +6dBm. It is available in QFN40 or WLCSP40 packages.
 
onsemi's RSL15-EVB evaluation board is intended for evaluating the performance and capabilities of the RSL15, and for developing, demonstrating, and debugging software applications for this device. It is designed to be used with the RSL15 Software Development Kit. The board includes the RSL15 wireless MCU with 512 kB of flash memory on board, an on-board SEGGER® J-Link® for easy code download and debugging, a JTAG debug port accessible via a 10-pin header, automatic power supply switching between battery and USB, and access to all MCU interfaces (GPIOs and test points) for measurement and prototyping. It also features two push-button switches, test points and GND hooks for easy probing, a CR2032 battery holder, and can be powered via USB connection with 5V regulated down to 3.0V by an on-board regulator.
 
onsemi also offers the RSL15 Software Development Kit (SDK), which provides drivers, libraries, sample code, and mobile apps (RSL Central and RSL FOTA for iOS/Android) to streamline development. It supports popular IDEs (onsemi IDE, Keil® µVision, IAR Workbench®) and includes documentation and firmware examples. It is comprehensive and yet easy to use.

The vast majority of hearing aids and glucose monitors on the market today use disposable batteries. Although these devices are designed to be low-power with a strong emphasis on longest lifetime, disposable zinc-air batteries last only 4-12 days in these devices, leading to frequent replacements and increased electronic waste. Rechargeable lithium-ion batteries address this issue by offering a much longer lifespan with many recharge cycles, despite a higher upfront cost.
 
To extend the operating time of these devices, power management is critical. onsemi's Battery Charge Controller HPM10 is a power management IC that provides a high-performance solution for rechargeable batteries in hearing aids and cochlear implant devices. It generates the voltage required by the hearing aid and manages the charging algorithms to optimize the number of charging cycles. The HPM10 supports silver-zinc and lithium-ion rechargeable chemistries, and can also detect zinc-air and nickel-metal hydride (NiMH) disposable batteries. The HPM10 features ultra-low power consumption, flexible battery type support, high-efficiency power regulation, non-volatile memory, a communication interface, and comes in a WLCSP29 package.
 
The HPM10 can supply the main hearing aid DSP with V_BAT, operate in a fully standalone mode, or communicate with the main DSP via GPIO. I²C is used to test and debug the HPM10 and to program the OTP. Communication with the charger is via a wired connection, with monitoring of charge status and fault conditions. onsemi has also developed the HPM10-002-GEVK evaluation kit, which includes an evaluation board, charger board, programming tools, and documentation to accelerate customer product development.

Consumer medical healthcare wearable devices are standing at the intersection of technology democratization and clinical value. From OTC hearing aids to continuous glucose monitors, these devices are no longer just passive data recorders but are gradually transforming into personal healthcare assistants that actively participate in health management. However, to truly achieve the leap from "consumer convenience" to "medical-grade trust," these devices must strike a perfect balance between miniaturization, ultra-low power consumption, sensing accuracy, and wireless connection stability. This is precisely where semiconductor technology plays a critical role. The onsemi solutions introduced in this document not only achieve size reduction and extended battery life at the hardware level, but also, through the integration of evaluation boards and software development kits, can significantly shorten the time from concept to market. They are an excellent choice for relevant application developers.