Development of a prototype for a mobile application to monitor hypertension from ECG data Open Access

Information provided by the Division of Cardiosurgery of the National Medical Center and the American Social Security Institute shows that ten people die every hour from myocardial infarctions, mainly due to congenital conditions, smoking, obesity, diabetes, and alcoholism. This situation, which has currently increased in people below 40 years of age, places heart disease as the main cause of death in America.^1,2

Over time, various devices have helped improve the quality of human health and detect and prevent multiple diseases. However, such devices are impractical; due to their large size and high prices, only institutions and hospitals can acquire them. Monitoring in critical patients is essential because their vital functions are supported by devices or drugs, so any abnormal deviation can cause a risk to life.³ Conventional electrocardiogram (ECG) monitors are large and attached to the patient by cables, limiting mobility and making medical procedures difficult. Existing devices are not within reach of all people since they are for use in hospitals and their sale requires specialized distributors. This prototype is designed to reach the hands of the general population, be easy to handle, and take readings that can be sent to the family doctor without the need to go to the clinic or to have the statistics of the behavior of the heart for a more complete analysis. This biometric device measures electrocardiographic signals clearly without taking up much space as in other similar instruments, in turn reducing not only the size but also the price of the equipment.⁴ There are similar devices for commercial sale. However, they are limited to measuring the heart rate and cannot graph the signal in real time. The importance of this project is defined by three main points: its size, its price, and its versatility.

The AD8232 integrated circuit is the main component in this prototype that leaves the previous designs made with operational amplifiers (OPAMPs) and arrays of instrumentation amplifiers in oblivion. Mounted on a card containing discrete elements, it is intended to extract, amplify, and filter tiny biopotential signals in the midst of noise, capable of monitoring electrocardiographic signals.⁵ The SparkFun single lead heart rate monitor-AD8232 card has a connector to place the electrodes on the patient and connects to an Arduino Due or Uno card. This Arduino card communicates with the computer through a USB-serial cable or a smart device by means of a Bluetooth circuit RN-41. The rest of the code for the application is developed in the Android operating system on a smartphone or using the G language of blocks from LabVIEW on a personal computer (PC).

In its current version, the prototype traces the impulses of the patient’s heart and provides the number of beats per minute in a box. In the tests carried out so far, its response is good. However, for its massive use, it still requires stricter laboratory tests, calibration, and certifications. With this prototype, it is intended that patients themselves have their own vision of the behavior of that important organ of the human body, the heart.

The heart is the motor organ of blood circulation. In humans, it is shaped similar to a triangular pyramid. It is situated in the chest cavity, the intermediate between the pleuropulmonary regions. It has a firm consistency and a reddish color.⁶ It has an approximate weight of 270 g in an adult man and a little less in a woman. It has four chambers: two upper ones called atria and two lower ones called ventricles. It is formed by a smaller percentage of muscular and fibrous tissue (Fig. 1). The heart has four cavities: two on the right and two on the left, separated by a medial septum; the upper pair of cavities is called atria, and the second pair is called ventricles.^7,8 The right atrium and right ventricle make up the right side of the heart, which is supplied with blood from the rest of the body by the superior and inferior venae cavae. This blood is taken up by the right ventricle, which pumps it into pulmonary circulation.

The four pulmonary veins drain blood from the lungs into the upper section of the left atrium, where it is distributed to the left ventricle. The left atrium and left ventricle combine to form the so-called left heart, which receives blood from the pulmonary circulation. This is oxygenated blood that has just exited the lungs. It is pumped from the left ventricle to the aorta artery and then to the rest of the body.

Valve structures prevent blood flow back across the heart.⁸ They are found near the atrioventricular orifices, between the ventricles and the outflow arteries. They are as follows:

• The tricuspid valve in the heart connects the right atrium to the ventricle on the opposite side of the heart.

• The mitral valve keeps the left atrium and ventricle distinct.

• The right ventricle is isolated from the pulmonary artery by a valve called the pulmonary valve.

• The aortic valve is located between the left ventricle and the aorta.

When the ventricular cavity contracts and expels part of its contents, the atrium fills with blood from the veins. When atrial pressure exceeds ventricular pressure, the valves open and the ventricles are filled.

One cardiac cycle is the period of time that begins at the beginning of one heartbeat and ends at the beginning of the following.⁹ The myocardium is responsible for producing the electrical impulses that cause heart contractions. This electrical impulse is produced when the sinoatrial node experiences a spontaneous action potential (or natural pacemaker). The atria contract when this internal pacemaker emits an electrical impulse. The signal’s next stop is the atrioventricular (AV) node. The AV node momentarily stops the signal, which then retransmits it along the ventricles’ muscle fibers, causing them to contract. Even though the SA node consistently releases electrical impulses, the heart rate might alter in reaction to physical activity, stress, or hormones. The configuration of the conduction system results in a 0.1 s delay from the atria to the ventricles (see Fig. 2).

The electrocardiogram (ECG) is the graph obtained with the electrocardiograph to measure the heart’s electrical activity in the form of a continuous graphic tape.¹⁰ It is the main instrument of cardiac electrophysiology and plays a relevant role in the encryption and diagnosis of cardiovascular diseases (Fig. 3).

The device and test conditions for a prototype for a mobile application to monitor hypertension from ECG data vary depending on the application. The application must compute statistical data on PR/RR/PP/TP intervals, QR/RS ratios, and other ECG characteristics. These data might track heart health changes. The application must compare ECG data to a healthy and unhealthy ECG database. This lets the app spot irregularities in healthy people. The app must warn if ECG data are abnormal. The user’s phone or tablet or the doctor might get these notifications.

Controlling application test conditions is also necessary. This ensures accurate and dependable application outcomes. ECG data are accurate when electrodes are properly positioned on the skin. ECG recordings should be lengthy enough to catch cardiac rhythm abnormalities. Controlling test conditions improves application accuracy and dependability. This would make the app useful for clinicians and individuals monitoring hypertension. Additional considerations for developing a mobile app prototype to monitor hypertension using ECG data are as follows:

The app should be simple so that patients would use it more often. The app should safeguard patient data. The app should be inexpensive and accessible to patients. This would make the software accessible to more individuals.

If these factors are taken into account, a mobile app prototype to monitor hypertension using ECG data may help hypertensive patients.

ECG waves are called P, QRS, T, and U waves and have positive or negative voltage. They originate from the depolarization and repolarization of different areas of the myocardium.¹¹ Each of the waves and segments is explained in detail below:

• P wave: The electrical signal that correlates with atrial contraction is the P wave. The left and right atria contract in unison.

• QRS: The electrical current that contracts the right and left ventricles is called the QRS complex. It is much stronger than the current that contracts the atria and has to compete with more muscle mass, which is why the ECG shows a higher deflection.

• T wave: The T wave represents the repolarization of the ventricles. The atrial repolarization wave is typically not noticed because the QRS complex obscures it. Electrically, cardiac muscle cells behave similar to charged springs that are triggered, depolarized, and contracted by a little impulse. Repolarization is the process of recharging the spring (also called action potential).

• U-wave: This wave is usually low-voltage and unrecognizable in most cases. It is inscribed behind the T wave and follows its same polarity; its presence is usually linked to hydroelectrolytic disorders, to the action of certain drugs, and more rarely to ischemia.

It is used to check to see if the heart is beating normally¹² or any anomalies, such as an irregular heartbeat, additional beats, or skipped beats.

• It identifies blocked coronary arteries (during or after a heart attack).

• It can be applied to find potassium, calcium, magnesium, or other electrolyte imbalances.

• It can make conductive anomalies detectable (atrioventricular block, bundle branch block, etc.).

• It can display the patient’s physical state before and after a stress test.

• It can describe the physiological conditions affecting the heart.

Although this is not always the case, it is generally accepted that an ECG signal that has been downsampled to 50 Hz will keep all of the necessary information even if it falls within the permissible range for ECG information, which is 0.05 up to 100 Hz.^13,14 However, this does not always hold true. Because the sensors that were used have the lowest frequency of 50 Hz, a band-pass Butterworth filter was applied to the frequencies spanning from 0.3 Hz all the way up to 50 Hz. This was done in order to remove any unwanted signals. Because it is a frequency that can really be achieved, the threshold frequency of 0.3 Hz was chosen. This frequency ensures that the baseline is completely removed without causing any distortion to the ECG signal.^15,16 We took into account this threshold and trimmed all of the signals so that they were in agreement with it. This was done since it has been shown via empirical research¹⁷ that segments of ECG signal lasting 30 s are adequate to create robust estimates in the relevant area of study. In addition, the 30 s signal length does not go beyond the projected amount of time necessary to carry out the traditional cuff-based blood pressure measurements. These readings are carried out in a customary manner. Traditionally, the information obtained from an electrocardiogram (ECG) is processed in such a way that it is possible to extract and examine the morphological aspects of the signal.¹⁸ 

ECG equipment is bulky and difficult to use in clinical settings.¹⁹ However, ECG technology has improved. Capillary electrometers recorded ECGs initially. Augustus Waller created it in 1887. The capillary electrometer was sensitive and heavy. String galvanometers were portable capillary electrometers. Willem Einthoven created it in 1901. The string galvanometer, albeit being huge and heavy, was more dependable than the capillary electrometer. Holter monitors are portable ECG devices that patients may use for long durations. Norman Holter created it in 1961. The Holter monitor helps diagnose arrhythmias and other cardiac issues. When the era of technology began to grow, new measuring instruments came out for the benefit of humanity; one of these is the electrocardiogram (ECG),²⁰ which has been used to measure the patient’s heart rate. It is not known exactly who invented the electrocardiogram since this is the result of an agglomeration of different investigations around the world (Fig. 4).

In hospital-based systems, there are extensions of terms for this type of device, such as Holter monitors;²¹ these monitors are responsible for keeping records of measurements 24 h a day and have from 3 to 12 electrodes working on the measurements. These systems are designed for prolonged conditions.

ECG patches (Fig. 5) are adhesive skin patches that record ECGs, an invention in the early 2000s. ECG patches are discrete and portable, making them popular for home usage. There are several portable ECG devices.^22–27 These devices are versatile and vary in size and complexity.²⁸ Smartwatches now include ECGs (Fig. 6). These ECGs are less precise than regular ones, but they may help monitor heart health. Wearable ECG devices capture ECGs. They can diagnose arrhythmias and follow heart health better than smartwatch ECGs. Mobile ECG applications (Fig. 7) are available. These applications allow smartphone or tablet ECG recording. These applications can monitor heart health, but the accuracy varies. ECG equipment makes heart health monitoring easier. These gadgets may identify heart issues early and improve heart health management.^29,30

• Early ECG equipment was bulky and difficult to move outside of a professional environment. Early ECG devices were less accurate. Low-quality electrodes and a lack of signal processing techniques contributed to this.

  1. Complexity: Early ECG machines required specific training to use. They were unavailable to many ECG monitor users.

  2. Price: Early ECG equipment was prohibitively costly.

  3. Early ECG devices also lacked critical functions such as the following:

  4. Memory: Early ECG devices had no memory; therefore, ECG records could not be kept or preserved. This made heart health monitoring harder.

  5. Wi-Fi: Early ECG devices did not have Wi-Fi, making it difficult to send ECG records to doctors.

  6. Graphing interface: Early ECG devices lacked a graphic interface, making ECG records difficult to see and comprehend.

New technology has solved several ECG device issues. Modern ECG devices are smaller, portable, accurate, easy to operate, and cheaper.^31–33 Memory, Wi-Fi, and graphing interfaces were absent in early ECG devices. These developments make ECG monitoring easier for those who require it. ECG devices can diagnose, treat, and monitor heart health. Early ECG devices also lacked memory, Wi-Fi, and graphics. Since early ECG devices had no memory, ECG records could not be kept or preserved. This made heart health monitoring harder. Those devices did not have Wi-Fi, making it difficult to send ECG records to doctors. In addition, they lacked a graphic interface, making ECG records difficult to see and comprehend. Modern ECGs need these capabilities. Memory stores ECG records to monitor heart health changes over time. A Wi-Fi connection lets doctors and other healthcare providers swiftly evaluate and act based on ECG readings. Doctors may immediately spot problems in ECG data using a graphic interface. These functionalities make ECG monitoring more accessible. ECG equipment can now diagnose, treat, and monitor heart health. Early portable ECG equipment could not monitor all of the symptoms presently deemed critical for heart disease diagnosis.^34–36 Early ECG equipment could not track symptoms such as the following:

1. Heart rate variability: It is the time between heartbeats. Latest ECG equipment measures the heart’s response to stress and exercise. Early portable ECG machines could not monitor heart rate variability; hence, they could not determine heart health.

2. QT interval: The ECG QT interval is the period between the Q wave and the T wave. It measures cardiac repolarization time following a beat. Early portable ECGs could not monitor the QT interval; hence, they could not determine arrhythmia risk.

3. ST segment: The ST segment is the ECG segment between the QRS complex and the T wave. It measures cardiac electrical activity. Early portable ECG equipment could not measure the ST segment and determine heart attack risk.

In addition to these symptoms, early portable ECG equipment could not measure blood pressure, blood oxygen levels, or body temperature, which might impair heart function. Early handheld ECG devices were unreliable for detecting and treating heart disease. New technologies have produced more advanced ECG equipment that can monitor more symptoms. These technologies are diagnosing and treating a range of cardiac issues earlier and more precisely.

• For the design of the prototype of an ambulatory electrocardiograph,³⁷ it is necessary to take into account the specifications of the AAMI standard (Association for the Advancement of Medical Instrumentation):³⁸ 

  1. Frequency response: The response of the instrument must be flat within ±0.5 dB in the frequency range of 0.14–25 Hz, and the response to a sinusoidal signal of constant amplitude must extend up to 100 Hz with a drop no greater than 3 dB.

  2. Input impedance: The input impedance between any electrode and the ground must be greater than 5 MΩ. This value is adequate to obtain a signal without distortion as long as the value of the impedance between the skin and the electrode is less than 30 kW. The instrument must not allow a current flow greater than 1 mA through the patient.

  3. Input dynamic range: The electrocardiograph must be able to respond to different voltages of 0.5 to 10 mVp-p.

  4. Gain: The equipment must have three gain values: 5, 10, and 20 mm/mV (which correspond to wins of 500, 1000, and 2000, respectively).

  5. Common Mode Rejection Ratio (RRMC): When all the electrodes are connected to a 120 V rms source at 60 Hz through a 22 pF capacitor, it should cause a deflection of less than 20 mmp-p. This is equivalent to having an RRMC of ∼100 dB at that frequency.

  6. Patient protection: The patient or operator must be protected from current flows greater than 20 mA from any electrode to the ground, with a test voltage of 120 V at 60 Hz, by means of an isolation system or the use of batteries.

The block diagram shown in Fig. 8 represents the different modules of the project for its development. It starts from the sensor layer, which contains the hardware elements in which the analog signal processing is carried out, all in a single integrated circuit called the AD8232 heart rate monitor from the manufacturer SparkFun. The management and treatment of the digital signal happen through an Arduino board. It also contains a user interface that can be an application on a device with an Android operating system or a LabVIEW program on the PC that analyzes the signals. This entire design process requires different tools to develop each of the parts of the diagram.

SparkFun created the AD8232, a tiny chip with the specific purpose of detecting heart electrical activity. An electrocardiogram, or ECG, can be used to monitor this electrical activity. The AD8232 is made to extract, amplify, and filter tiny biopotential signals in the presence of noise, such as that present while placing electrodes far away and in motion.

There are nine connections on the AD8232 heart rate monitor. Although they originate from IC pins, these connections are solderable holes or header pins, as seen in Fig. 9. Five of the board’s nine pins should be connected to the Arduino. As shown in Table I, the five pins one need are GND, 3.3 V, OUT, LO-, and LO+. RL, LA, and RA describe the ECG lead positioning, which represents the right leg, left arm, and right arm, respectively.

The Bluetooth device usually works in the 2.4 GHz frequency bands, which makes it optimal for data transfer; for this project, the matte silver Bluetooth module (SparkFun) is used.

This Bluetooth module is compatible with the Android platform and can be used in enslaved person or master mode; in the slave mode, it is ready to send and receive data from another device, but it is not possible to initiate communication between the two since in this mode, it is subject to device commands. The SparkFun module can work in both ways by changing its programming. For convenience, this module is programmed as a master type, and it contains a UART (Universal Asynchronous Receiver/Transmitter) interface for serial data transmission to the microcontroller. In this, the data of the analog signal received in the ADC (Analog to Digital Converter) of the microcontroller are sent at a speed of 115 200 bauds per second. To connect the Bluetooth module to the microcontroller, its TX (Bluetooth) pins must be crossed to RX (uC) and RX (Bluetooth) to TX (uC), as shown in Fig. 10.

For the connection between the Arduino and the Bluetooth module, it must be taken into consideration that:

• the module works at a low state TTL level, that is, 5 V;

• the RX and TX pins on the board are tied to the same USB link.

In the development of the application, a window was implemented to view the sample in real-time, which is obtained from the signal emitted by the electrodes and digitized by the device. With LabVIEW, virtual instruments are built with programming in the G language (Molina and Jiménez, 2012). With the front panel, the user interface is built, and the block diagram contains the graphic source code, which implements the serial data acquisition subroutines, their treatment, and their presentation.

After activating the Bluetooth function, it is necessary to configure the mandatory records and data necessary for the correct operation of the application, for which the “Menu” key on the cell phone is pressed or touched so that the application menu is displayed. Then select the option to set up.

Regardless of the selection mode and after data configuration, it is necessary to link the Bluetooth device of the cell phone with the RN-41 Bluetooth module of the circuit board in order to start receiving the data coming from the circuit board. For this, select the connect option in the application menu to search for Bluetooth devices around. The device to select is the RN-41 Bluetooth module on the circuit board that corresponds to the name FireFly-D363.

Once the connection is made with the FireFly-D363 device, the data are received from the plate, which is connected to the person, and the application begins to work, graphing the cardiac cycle and the heart rate on the main screen of the application.

This mobile app prototype uses ECG data to monitor hypertension.

Right arm: RA; left arm: LA; right leg: RL; or left leg: LL. ECG electrodes enhance filtered ECG signals on limbs. Three electrodes are generally used. One is for the earth (green), and the other two are for signals (red and yellow). Yellow and green are placed on the same side. Computer labs tested the prototype, ensuring ECG quality. The prototype monitored hypertension. The prototype could track hypertensive patients. The prototype may improve hypertension monitoring and patient health in numerous scenarios. If we consider quiet environments, it reduces ECG signal interference. ECG signal interference is reduced if we avoid electrical interference. The temperature and humidity also comfort patients during suffering. These criteria may determine an application’s best test environment.

A smartphone app prototype to monitor hypertension using ECG data might help physicians diagnose cardiac problems. The application program may collect and save ECG data from the user’s smartphone or tablet. The program may analyze these data for irregularities. The program may produce statistical data on PR/RR/PP/TP intervals, QR/RS ratios, and other ECG parameters. These data might track heart health changes. The program may compare ECG data from healthy and ill people. This lets the app spot irregularities in healthy people. If ECG data are abnormal, the app may warn. The user’s phone, tablet, or doctor might get these notifications. This helps people understand their risk factors and make health choices. A mobile app prototype to monitor hypertension using ECG data might be beneficial. The app might help detect hypertension sooner, allowing for earlier treatment. The feedback from the app might help patients stick to their treatment plans. The app might cut doctor visits and other medical testing.

Overall, a mobile app prototype to monitor hypertension using ECG data might benefit clinicians and patients. The app might improve hypertension diagnosis, patient compliance, and healthcare costs.

A mobile app prototype to monitor hypertension using ECG data will need varied power levels depending on usage. Estimates might be wide. ECGs use minimal power. ECG electrodes use milliamperes. ECG processing uses more power. The program must increase the ECG signal, filter noise, and evaluate data. This needs hundreds of milliamperes. ECG frequency impacts battery life. ECG recording drains batteries. Lithium-ion batteries have 2000 mAh. This allows for 8 h of ECG recording. If ECGs are recorded sporadically, the battery may last several days. Battery life is battery-specific. Larger batteries last longer. High-capacity batteries cost more. ECG data-based hypertension monitoring uses less electricity. Lithium-ion batteries power ECG recording for hours. ECG electrodes use milliamperes, and electrodes need more power. The ECG amplifier draws several 100 mA. Amplifier gain affects power consumption. The noise filters draw milliamperes, and filter bandwidth affects power usage. The ECG processor draws a few 100 mA. Power usage depends on the complexity of the data analysis method. These things may reduce gadget power consumption. This ensures a long battery life and prolonged usage.

In specific circumstances of the experiments, we used a battery that had a capacity of 2000 mAh to monitor the electrocardiogram. Before the battery expired, the device was capable of recording continuously for around six hours. Both the pace at which data are sampled and the duration that they are recorded have an effect on the quantity of memory that is required to store the data. For instance, if the recording is going to continue for six hours and the sampling rate is going to be 125 Hz, then the quantity of memory that is required is going to be 2.65 MB.

The amount of memory that is necessary for data storage may sometimes be fairly substantial. If you want to do long-term ECG monitoring, it is essential that you make use of a power source that is connected to a line of electricity or a battery that has a lengthy lifetime.

There is a low-cost, portable, easy to use, and very accessible device for the pocket of the public still in development, with only an Arduino card, a specific purpose SparkFun 8232 cardiac monitoring card, a Bluetooth communication device, a USB link, a cable with three electrodes, and some programming code developed in Android and LabVIEW. At the moment, the progress of this prototype is supported by the graph provided by the application, with some variation in shape and inherent noise depending on the individual under study and the placement of the sensors. Such graphs in which the P, QRS, T, and U segments correspond to the waveform are shown in the reference literature, and the graphs are displayed in other devices for the same purpose.

Bluetooth or USB links the prototype to a PC or smartphone.³⁹ Bluetooth makes wireless connections more convenient. Bluetooth may be unsuitable for high-quality data applications. In our experiments, we connected the prototype to a PC or smartphone using Bluetooth and a USB link. Bluetooth made short-term testing easy. For long-term testing, a USB link worked well. Bluetooth’s range is limited, so far-flung gadgets may not operate. Bluetooth requires more power than a USB link. A USB link is safer than Bluetooth. These factors influence an application’s connection mechanism.

For the purpose of writing this article, tests were carried out on a group of 19 people, including children, adolescents, youths, adults, and older adults, chosen randomly to form a sample, according to the age distribution presented in Fig. 11.

Figure 12 shows the ECG waveforms: ECG signal 1 (row 1), ECG signal 2 (row 2), and ECG signal with noise (row 3). The x-axis is the time, and the y-axis is the amplitude. Table II shows the values for the average heart rate.

An electrocardiogram (ECG) includes two parameters that are particularly significant: the ST interval and the PR interval. The amount of time that elapses between the completion of the QRS complex and the start of the T wave is referred to as the ST interval. The amount of time that elapses between the start of the P wave and the start of the QRS complex is referred to as the PR interval. The ST interval has a mean of 0.12 s and a standard deviation of 0.02 s. This indicates that the standard deviation in the ST interval is often within 0.02 s of the value that is considered to be average. The standard deviation for the PR interval is 0.03 s, while the average PR interval is 0.18 s. This indicates that the standard deviation of the PR interval is often within 0.03 s of the value that is considered to be average.

In terms of temporal resolution, the prototype of the device that is being developed for monitoring ST intervals has a frequency resolution of 125 Hz. This suggests that the apparatus is collecting 125 measurements of the patient’s electrocardiogram (ECG) signal every single second. It is essential to have a high temporal resolution when measuring the ST interval since this ensures that the ST segment is recorded accurately.

In the event that the temporal resolution is not good enough, the ST segment may be undersampled, which would lead to an inaccurate measurement. If the temporal resolution is too high, the needed quantity of memory can end up being too much for the system to handle as well.

The number of datapoints would be 125 times 60, or 7500, for an ECG recording that is exactly 1 min long. Using this information alone would be sufficient to make an accurate measurement of the ST interval. Table III shows the time resolution of the prototype device for different recording durations.

From the data obtained, it can be seen that the heart rate of children and adolescents is slightly elevated, which is according to the information obtained, completely normal for their age; because of the demand for blood supply, oxygen and nutrients in the body are inversely proportional to the size of the body; children and adolescents are also in continuous growth and development, and as they grow, their heart rate decreases until it stabilizes at normal values. The clinical analysis of the results obtained from the graphs is not the purpose or within our reach. The very purpose of the prototype is only to present the graph and deliver numerical data corresponding to the cardiac impulses of the individuals participating in the sample.

The prototype is good from the point of view of its architecture because of its very encouraging results and because any effort made to improve health care from home is very valuable to treat any symptom or ailment, even at home.⁴⁰ The price is below 500 dollars because in its construction, a specific purpose card is used that already includes signal amplifiers, comparators, and filters and because it provides a graph that clearly displays the cardiac impulses that, according to even the experts consulted, are similar to those presented by professional devices. The design can still be simplified with more versatile sensors, such as a bracelet or the like. It is still necessary to put the device in a further field evaluation, in which its results are compared with those of other devices for commercial use in the hands of specialists or even submit its response to a certified laboratory since, in the graph of the signal, there is a noise effect apparently due to lamps and radiation emitted by surrounding computers and also due to the sensitivity of the sensors when the patient ceases to be in the resting state no matter how little he is agitated. It is also necessary to develop the code so that the samples go to a broader database that allows a complete analysis. In the future work, the device could be connected by TCP or IP to the specialist since it is a low-frequency signal and requires little bandwidth. To the extent that such pending stages can be overcome, the reliability of the device’s measurements can be strengthened, but there is still much to be done to stop from it being just a good prototype.

In order to properly address the subject, the electrical characteristics of the ECG signal have been studied, as well as the benefits offered by the different development boards on the market. At the beginning of the project, the correct visualization of the electrocardiogram was proposed as the main objective. As has been observed, the representation obtained for the disposable electrodes is quite correct. The results for the ECG are satisfactory. Regarding breathing, it is an addition to the project since it is not part of the main objective; however, its representation is correct, although its clarity is not. The interface designed using LabVIEW provides a clear visualization of both signals. It allows one to configure the device and export the data to an external file. In addition, learning about the use of the serial port and filtering has been very satisfactory. The results of the project are, therefore, satisfactory with respect to the ex-post objectives. The most immediate implementations would be to replace communication via Arduino and PC with a wireless medium, such as Bluetooth. This option is easy, thanks to the HC modules designed for use with Arduino, which with only four pins is capable of communication. Finally, a more ambitious implementation would be to transfer the LabVIEW interface to a smartphone application following current trends in this type of portable device and through Bluetooth communication.

This research was funded by the Deanship of Scientific Research (DSR), Taif University, Taif, Saudi Arabia. The author, therefore, thanks the Deanship of Scientific Research for the technical and financial support (Project No. 202215).

The author has no conflicts to disclose.

Omar Mutab Alsalami: Project administration (equal); Resources (equal); Software (equal); Writing – original draft (equal).

The data that support the findings of this study are available from the corresponding author upon reasonable request.