What are Wearable Health Trackers?
A U.S. government report suggests more than 2 in 5 U.S. adults are affected by chronic conditions like obesity, diabetes and heart diseases. The advent of COVID-19 pandemic which was marked by social isolation and quarantine across the globe. Crude estimates of prevalence of these conditions among young adults ages 20 and over were reported to be 43% for men and 42.1% for women, and the same accounted for nearly US $173 billion medical expenditures as the pandemic progressed. In comparison to this, US fitness statistics suggest that –
- 1 in 5 adults take part in exercises each day
- 23% do the recommended amount of aerobic and muscle strengthening activity each week
- US $32 billion is the estimated value of the US gym health and fitness club market
- Yet 1 in 4 adults do not meet the recommended physical activity levels
Wearable health monitoring devices such as smartwatches, wristbands, pedometers, accelerometers, oximeters etc. are devices worn on a user or patient’s body which allow self-tracking of physical activity behavior and provide feedback. For example, daily step count, time spent at different levels/intensities of exercises done, approximate number of calories burnt, blood pressure and heart rate etc. IoT-based health tracking devices also eliminate the need for regular checkups and interactions with healthcare professionals, as users are constantly reminded of their fitness estimates by these devices. Moreover, patients in intensive care units, who needed to be continuously checked and posed challenges for hospitals with limited staff previously, can be easily monitored using these devices. These devices were especially useful during the pandemic where hospitals were working at full capacity and medical personnel were deployed in environments that indicated a high risk of infection. The hardware devices are equipped with sensors, microcontroller units and interface, Bluetooth, that collect real-time data on important health indicators like pulse rate, body temperature, blood oxygen saturation, blood sugar level, sleep patterns etc. and wirelessly transmit the same to a cloud-based storage system and thereto a web-based interface that can be accessed, visualized and assessed by healthcare specialists at all times for remote monitoring. The smart wearable market is forecasted to record a shipment of over 560 million devices as of 2024 with Apple gaining the largest share of around 52.5% of the same, followed by Samsung.
Total adults who met federal physical activity guidelines using health monitor bands in 2016
Steps of Wearable Device Design and Development
1. Identify Key Health Metrics:
These may include vital signs such as blood pressure (120/80 mmHg), body temperature (36.5-37.5℃), oxygen saturation (SpO2, >95%), activity levels such as steps taken, calories burned or taken, sleep patterns, or specialized metrics such as blood glucose level, Electrocardiogram (ECG), hydration levels etc.
2. Selection of Sensor:
Every metric requires a specific type of sensor that is enclosed for measurement due to sensitivity towards light etc. For example, photoplethysmography (PPG) sensors for heart rate and SpO2, accelerometers for tracking activity, thermistors for body temperature, contact lens sensor for intraocular pressure (IOP) blood sugar and sepsis (such as by Herpes Simplex Virus-1) through tears, piezoelectric biosensor matrix for monitoring lactic acid, glucose, uric acid and urea, electromagnetic one-touch activated blood multi-diagnostic system (OBMS) for monitoring blood glucose and cholesterol, smart bandage sensor for optical pH monitoring, ionic bioelectric skin patch for monitoring pressure, pH, temperature and ECG data, thermography or hyperthermic recessive lens for monitoring Interleukin-1 alpha (IL-1α) against inflammation, fever, wound, microfluidic sweat sensor patches for assessing distribution of Vitamin C and more.
3. Hardware Design:
a. Microcontrollers: A suitable microcontroller (Medical grade if required) needs to be selected for the health monitor band which can handle multiple sensor inputs and requires low power consumption. For example, Espressif Systems’ ESP32 low-cost System on Chip (SoC), ESP8266, RISC-V architecture-based ESP32-C3, Raspberry Pi Pico based on RP2040 chip with Bluetooth connectivity, input/output options, support for software libraries and programming languages such as MicroPython, C etc., STMicroelectronics’ STM32 Series microcontroller with wireless communication (Bluetooth) based on Arm Cortex-M microprocessors with low power consumption, high processing power, compatibility for IoT systems, programming languages like Python, C, and a wide range of peripherals such as ADC, SPI, I2C, UART etc.
Other options include Arduino Nano based on ATMega328P chip with built-in USB connectivity and functioning with devices like I2C, SPI, UART, PWM etc., Teensy microcontrollers based on ARM Cortex-M7 processors with high processing power, extensive input/output options, multiple sizes, configurations, suitability for fast and complex calculations, advanced communication interfaces like I2C,, SPI, UART, support for programming languages like Arduino, C, Python etc., Nordic Semiconductor’s nRF52840 microcontroller based on ARM Cortex-M4 processor architecture with low power consumption, comprehensive development ecosystem and support for wireless protocols like Bluetooth Low Energy (BLE), Bluetooth 5, Thread, Zigbee, ANT etc.
A few microcontrollers, specifically for smartwatches include LilyPad Arduino with sewable LEDs, sensors, buttons, battery holders, Adafruit Flora with a GPS component, Bluetooth module, NeoPixels LEDs, Adafruit GEMMA with built-in switches, battery connectors, micro USB for programming, TinyLily Mini, StitchKit etc.
b. Display: Most of the fitness tracking smartwatches and other devices come with active-matrix organic light-emitting diode (AMOLED) thin-film-display made of electroluminescent material and active matrix, that allow each pixel to emit light, thus featuring higher contrast ratios, ultra resolution, Bluetooth connectivity and vibrant colors.
c. Others: The wearable tech design must consider power-efficiency, by incorporating energy harvesting techniques, if possible. A communication channel via Bluetooth with the message queue telemetry transport (MQTT) protocol is required for data transmission from controller to the cloud storage server and then to a mobile app or dashboard (Adafruit IO). The device’s design must be easy to operate, understand and maximize the comfort level of the user.
Various types of microcontrollers used in wearable device design and development
4. Software Development:
This step includes the development of firmware that processes sensor data and manages device operations. It may also include application development for data visualization, user interaction and alerts. Cloud integration services for data storage and data analysis in clinical research are necessary for remote patient monitoring. It is important to consider data visualization design principles that harbor understandable and appropriate charts, graphics and trends. There are certain free web-based services such as If This Then That (IFTTT) that help to connect various devices, sensors, apps, cloud servers etc. with each other and send notifications to the caregiver or healthcare professional in case of anomalies detected.
5. Prototyping & Testing:
One can go for MVP development services that utilize CAD for developing health tracking device prototypes. Rigorous testing is required to ensure accuracy, reliability and comfort for the patient or user. In most cases, clinical trials are necessary to validate the medical accuracy of the device. Sometimes, there is latency observed on IoT platforms due to the location of the server, network conditions, traffic volume on the platform etc. Thorough testing against erroneous data due to inaccurate placement or misplacement of the sensor, environmental effects causing body temperature variations, motion artifacts, light scattering from other sources etc.
6. Regulatory Compliance & Data Security:
The wearable device design needs to meet regulatory standards such as the FDA, CE for medical devices and obtain necessary certifications and approvals. Robust encryption and security measures need to be implemented to protect user’s medical data. Administrative control, where only admins can read, write, alter, and save data, while users can only view it, can be utilized. Compliance with data protection and healthcare industry regulations such as GDPR and HIPAA must be ensured.
7. User Experience & Design:
The ergonomic design and comfort around the usability of the device need to be focused upon. The interface must be user-friendly and aesthetically pleasing on implementation, such as for devices that work on the basis of AI breast cancer detection.
8. Market Launch & Scaling:
A marketing strategy suitable to reach the specific target audience needs to be put in place. A plan around scalable manufacturing processes and quality control protocols to maintain the device’s consistency, reliability and compliance is required. It is important to provide customer support and regular updates to improve the device based on user feedback post-deployment.
Advantages & Challenges of Wearable Health Trackers
Let us discuss further some of the advantages and challenges of designing health tracking devices.
Advantages
Wearable technology in health monitoring showcases many advantages, a major one being portability, since this feature allows users to monitor their health irrespective of location or time. It can be easily worn to indicate health parameters such as heart rate, sleep quality and exercise intensity, and this helps them understand their health conditions for taking suitable actions. Another important feature of wearable tech design is real-time monitoring of health data, its analysis and interpretation in the form of charts, images etc. on a user-friendly interface, smartphones and other devices that allow users to intuitively understand their health status and progression. Smart wearables can be personalized according to the user’s needs and health-related goals, for example, walking a fixed number of steps on a daily basis, managing heart rate in the recommended range during swimming etc. The device provides custom regulated updates, alerts, reminders and suggestions that assist users in reaching their specific goals.
In the case of health monitoring trackers deployed in hospitals and centers, healthcare personnel can monitor their patients and engage in other important activities like attending surgeries, medical symposiums on high-risk cases etc. at the same time through their tracking apps. Patients can easily go about their rooms and nearby areas without being connected to large monitoring devices. Also, health monitor bands cost much less than the latter and can read miniscule signals in terms of biofluids which larger devices and healthcare personnel may not be able to notice until visible symptoms occur. They can receive real-time updates on extremely vulnerable and critical patients while they are under their assistants’ care, such as those suffering from asthma, chronic obstructive pulmonary diseases (COPD), post-cerebrovascular accidents (ischemic, hemorrhagic strokes, TIA clots), cystic fibrosis, cirrhosis, schizophrenia, heart-related conditions etc. They are especially useful to track health parameters of patients suffering from airborne communicable diseases like COVID-19 (SARS-CoV-2), Influenza, Tuberculosis, Measles (Morbillivirus), Chickenpox (Varicella-Zoster Virus), Whooping Cough (Bordetella Pertussis), Pneumonia etc. without direct interaction. Highly sensitive devices can detect and alert professionals regarding miniscule anomalies and irregularities in the parameters and prevent impending accidents such as heart or organ failure etc. on time.
Types of sensors used in wearable product design and development
Challenges
Smart wearables also pose certain health monitoring challenges. Many times, the comfort and ease of use of the devices are a major concern since they need to be in constant contact with the patient or user. The user may not prefer wearing the device if they are uncomfortable with it and may remove it frequently causing errors in analysis, data collection and health monitoring statistics. In the case of critical patients, it is highly important for the device to be in contact, for example, sensing eye lenses, continuous glucose monitor (CGM) or diabetes patch that monitors glucose levels in the interstitial fluid etc. Therefore, it is important for designers to integrate user feedback to ensure maximum user comfort level of the wearable product design, along with its function and performance. One more challenge is the limitation of sensors and algorithms leading to inaccurate data and false positives. One can only imagine the stress that may occur due to incorrect alerts related to heart rate monitoring caused by device movement or contact interference. Embedded designers need to continuously work on improving data accuracy, reliability of the algorithm and sensor credibility.
Another common issue with wearable product design is low battery life, mainly because of the high volume, power consumption, frequent charging requirements and limited battery capacity (5V+). This makes it very difficult for users to go out for exercise while tracking their health. Efficient and convenient charging methods and extended battery life with device functionality maintenance are the need of the hour, which are likely to improve user satisfaction and device usability. The most important issue related to smart wearables is security of sensitive information related to the user’s health. Privacy around this is not guaranteed due to data transmission and connectivity, which are subjected to potential leakage and attacks such as distributed denial of service (DDoS) cyberattacks on Microsoft’s services and products like Holo smartwatch. Researchers and designers need to implement necessary security measures such as encrypted communication, multi-factor authentication etc. to protect user’s data.
Mining the Frontier of Wearable Tech Design
It is fair to conclude that IoT-based health monitoring wearables represent significant advancements in the healthcare industry, as they assist personnel working in this industry to gain real-time insights into their patients. Countries like the U.S. are moving towards an era composed of a healthier population that is aware of fitness trends and relies on smart wearables for tracking health-related parameters and important metrics before they escalate and lead to unfavorable chronic conditions. Real-time monitoring helps them manage their health issues and take effective measures in time. Health trackers have various advantages such as portability, real-time updates, feature customization and intuitive data visualization. At the same time, device designers, R&D and innovation firms like KritiKal Solutions are continuously working to overcome challenges such as low battery life, data security, accuracy and comfort to further improve the usability of the device and user satisfaction.
With continuous innovation in wearable health monitoring devices, one can expect the application prospects of health monitoring to become broader soon. KritiKal has designed and developed different types of wearable health monitoring devices for various SMBs and Fortune 500 companies, such as in vitro micro diagnostic devices, sensor matrix-based wearable diagnostic tools, bio-sensing devices, electrotherapeutic medical devices for pain, insomnia, depression, computer vision applications for healthcare, and many more. Please mail us at sales@kritikalsolutions.com to learn more.
Yash Kishore works as a Senior Embedded Engineer at KritiKal Solutoons. He has over 8 years of experience working with embedded systems, microcontrollers, electronics and is proficiently skilled in hardware designing and engineering, analog circuit designing, VHDL, BOM, CAD and more. He has helped KritiKal in delivering various projects to some major clients.