Comparing DIY Heart Rate Monitor with Smartwatch
Exploring Electrical Heart Rate Detection and Building a DIY Heart Rate Monitor
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As an enthusiast of wearable technology, I've been fascinated by the heart rate detection feature in my commercial smartwatch. However, after two years of use, I noticed that the heart rate detection became sluggish and unreliable. In this article, we'll delve into the world of electrical heart rate detection, explore how it works, and build a DIY heart rate monitor to compare its recorded data with that of my commercial smartwatch.
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Understanding Heart Rate Detection
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The heart rate detection feature in my commercial smartwatch uses a combination of two green LEDs and a photodetector to measure the changes in blood flow through my skin. This technique is known as photoplethysmography (PPG). By calculating the time between two or more peaks, we can easily obtain the heart rate.
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Building a DIY Heart Rate Monitor
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To build our DIY heart rate monitor, we'll need a few components: an Arduino Pro Mini, a MAX30100 heart rate sensor, and some hookup wire. We'll connect the power and data wires of the sensor to the Arduino board and use a library to interact with the sensor registers.
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After uploading the code to the Arduino board, we can test the heart rate monitor by pressing our finger onto the sensor. The serial monitor will display the detected heart rate values. However, we notice that the sensor requires firm contact with the skin and some algorithms to get a stable heart rate.
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Due to the limitations of the MAX30100 sensor, we opt for an alternative: the Groove Heart Rate Sensor from Seed Studio. This system combines a PAH-H001EI heart rate sensor with an STM32 microcontroller, offering better performance and ease of use.
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After testing the new sensor system, we create a schematic for our DIY heart rate monitor, adding components such as an OLED display, a battery with a 3.3V regulator, a switch for power, and a microSD card module.
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We write Arduino code using three different libraries to control the system and upload it to our finished device. The OLED display shows us the current heart rate every second, and we can see that the Arduino perfectly logs all the displayed values.
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Designing a Case for Our DIY Heart Rate Monitor
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Using Fusion 360, we design a case for our Arduino system and 3D print it with a Prusa i3 MK3. We add an elastic band to the case and place all the electronics inside, securing them temporarily with hot glue.
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Testing Our DIY Heart Rate Monitor
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We test our DIY heart rate monitor by wearing it on our arm and comparing its recorded data with that of our commercial smartwatch. After a 30-minute run, we notice some issues with the DIY system but also see that both devices track our heart rate accurately.
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We import the recorded values into Excel to create a graph and compare the data from both devices. Although there are some minor differences, both devices show similar results, indicating that my commercial smartwatch still works fine.
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| Heart Rate |
The number of heartbeats per minute (bpm) that an individual's heart is pumping blood. |
| Background |
A normal heart rate varies from person to person, but a typical adult heart rate is between 60-100 bpm. Heart rate can be influenced by factors such as age, fitness level, and emotions. |
| Resting Heart Rate |
The heart rate measured when an individual is at rest and not engaging in any physical activity. A normal resting heart rate for adults is typically between 60-80 bpm. |
| Maximum Heart Rate |
The highest heart rate achieved by an individual during intense exercise or stress. Maximum heart rate decreases with age and can be estimated using the formula: 220 - age = maximum heart rate. |
| Abnormal Heart Rates |
Heart rates that fall outside of the normal range, such as tachycardia (rapid heartbeat) or bradycardia (slow heartbeat), can be indicative of underlying medical conditions and should be evaluated by a healthcare professional. |
Comparing DIY Heart Rate Monitor with Smartwatch |
| Introduction |
With the increasing popularity of wearable technology, many people are turning to smartwatches and fitness trackers to monitor their heart rate. However, for those who prefer a more hands-on approach or want to save money, DIY heart rate monitors have become a viable option. In this article, we will compare the features, accuracy, and practicality of DIY heart rate monitors with commercial smartwatches. |
| What is a DIY Heart Rate Monitor? |
A DIY heart rate monitor is a self-built device that uses sensors and microcontrollers to measure the user's heart rate. These devices can be made using various components, such as Arduino boards, pulse sensors, and LCD displays. They often require some programming knowledge and technical expertise to assemble and calibrate. |
| What is a Smartwatch? |
A smartwatch is a commercial wearable device that offers various features, including heart rate monitoring, GPS tracking, and notification alerts. Smartwatches are designed to be user-friendly and often come with pre-installed apps and software. |
| Features Comparison |
| Feature |
DIY Heart Rate Monitor |
Smartwatch |
| Heart Rate Monitoring |
Limited to heart rate monitoring only |
Includes heart rate monitoring, GPS tracking, and other features |
| Accuracy |
Variable, depending on sensor quality and calibration |
Generally accurate, with some minor variations |
| Cost |
Low cost, often under $50 |
Higher cost, ranging from $100 to over $500 |
| User Interface |
Limited display and interaction options |
Touchscreen interface with customizable watch faces and apps |
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| Practicality Comparison |
| Aspect |
DIY Heart Rate Monitor |
Smartwatch |
| Convenience |
Requires manual assembly and calibration |
Pre-assembled and ready to use out of the box |
| Portability |
Often bulky and not wearable |
Designed to be worn on the wrist, compact and lightweight |
| Battery Life |
Variable, depending on power source and efficiency |
Typically lasts several days or weeks on a single charge |
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| Conclusion |
While DIY heart rate monitors offer a cost-effective and customizable solution for those who want to monitor their heart rate, they often require technical expertise and may lack the convenience and practicality of commercial smartwatches. Smartwatches, on the other hand, provide a user-friendly experience with a wide range of features, but come at a higher cost. Ultimately, the choice between a DIY heart rate monitor and a smartwatch depends on individual preferences and needs. |
| Q1: What is a DIY heart rate monitor? |
A DIY heart rate monitor is a self-made device that measures heart rate using various components such as sensors, microcontrollers, and LEDs. |
| Q2: How does a DIY heart rate monitor work? |
A DIY heart rate monitor works by detecting changes in blood flow or oxygen levels in the body using sensors, which are then processed by a microcontroller to display the heart rate. |
| Q3: What is a smartwatch? |
A smartwatch is a wearable device that can track various health and fitness metrics, including heart rate, in addition to providing notifications and other features. |
| Q4: How does a smartwatch measure heart rate? |
A smartwatch measures heart rate using photoplethysmography (PPG), which involves shining light through the skin to detect changes in blood flow. |
| Q5: Which is more accurate, a DIY heart rate monitor or a smartwatch? |
A smartwatch is generally more accurate than a DIY heart rate monitor due to its advanced sensors and algorithms, as well as its ability to take multiple readings per second. |
| Q6: What are the advantages of using a DIY heart rate monitor? |
The advantages of using a DIY heart rate monitor include cost-effectiveness, customization, and educational value, as users can learn about electronics and programming. |
| Q7: What are the disadvantages of using a DIY heart rate monitor? |
The disadvantages of using a DIY heart rate monitor include limited accuracy, potential for errors or inconsistencies, and lack of additional features compared to a smartwatch. |
| Q8: Can a DIY heart rate monitor be used for medical purposes? |
No, a DIY heart rate monitor should not be used for medical purposes due to its limited accuracy and potential for errors or inconsistencies, which could lead to incorrect diagnoses or treatments. |
| Q9: How does the cost of a DIY heart rate monitor compare to a smartwatch? |
A DIY heart rate monitor can be significantly less expensive than a smartwatch, with costs ranging from $10 to $50, whereas smartwatches typically range from $100 to $500 or more. |
| Q10: Which is more convenient to use, a DIY heart rate monitor or a smartwatch? |
A smartwatch is generally more convenient to use than a DIY heart rate monitor due to its compact design, user-friendly interface, and ability to track multiple metrics simultaneously. |
| Rank |
Pioneers/Companies |
Contribution |
| 1 |
Polar Electro Oy |
First wireless heart rate monitor (1977), pioneer in wearable technology. |
| 2 |
Garmin Ltd. |
Introduced first GPS-enabled smartwatch with heart rate monitoring (2014). |
| 3 |
Apple Inc. |
Popularized wearable technology with Apple Watch, including built-in heart rate monitoring (2015). |
| 4 |
Fitbit, Inc. |
Developed affordable, user-friendly fitness trackers with continuous heart rate monitoring (2014). |
| 5 |
Samsung Electronics Co., Ltd. |
Released Galaxy Watch with built-in heart rate monitoring and integration with Samsung Health (2018). |
| 6 |
Mio Global |
Introduced first wrist-based, continuous heart rate monitor without a chest strap (2013). |
| 7 |
TomTom N.V. |
Developed Runner watch with built-in heart rate monitoring and GPS tracking (2013). |
| 8 |
Suunto Oy |
Released Core All Black watch with heart rate monitoring and outdoor navigation features (2015). |
| 9 |
Coros Wearables, Inc. |
Developed Pace smartwatch with built-in heart rate monitoring and advanced running dynamics (2018). |
| 10 |
Xiaomi Inc. |
Released Mi Band series with affordable, feature-rich fitness trackers including heart rate monitoring (2015). |
| Category |
DIY Heart Rate Monitor |
Smartwatch |
| Sensor Technology |
Photoplethysmography (PPG) using a single LED and photodiode |
PPG using multiple LEDs and photodiodes, sometimes combined with electrocardiography (ECG) |
| Sampling Rate |
Typically 100-200 Hz, depending on microcontroller capabilities |
Usually 250-500 Hz, sometimes up to 1 kHz |
| Resolution |
8-10 bits, depending on analog-to-digital converter (ADC) resolution |
12-16 bits, providing higher signal precision |
| Accuracy |
±2-5 beats per minute (bpm), depending on signal processing and filtering |
±1-3 bpm, often with advanced signal processing and noise reduction techniques |
| Power Consumption |
Typically in the range of 10-50 mA, depending on microcontroller power management |
Usually around 100-500 μA, due to more efficient hardware and power-saving features |
| Data Processing |
Simple signal processing using a microcontroller's built-in ADC and digital signal processor (DSP) |
Advanced data analysis using dedicated application-specific integrated circuits (ASICs) or DSPs, sometimes with machine learning algorithms |
| User Interface |
Simple LED indicators or LCD displays for basic heart rate information |
Color touchscreens with user-friendly interfaces and customizable watch faces, often with voice assistant integration |
| Connectivity Options |
Limited to serial communication (e.g., UART) or simple wireless protocols like Bluetooth Low Energy (BLE) |
Multitude of options, including BLE, Wi-Fi, GPS, and cellular connectivity for data synchronization and notification forwarding |
| Software Compatibility |
Custom firmware development required, often with limited community support |
Commercial operating systems like Wear OS or watchOS, offering extensive app libraries and developer resources |
| Cost |
Low-cost components (≈ $10-50) for a basic DIY setup, but potentially requiring additional tools and expertise |
Premium pricing (≈ $200-1000+) due to advanced hardware features, high-quality construction, and software support |
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