Arduino programmable transcutaneous electrical nerve stimulation - Option 1

Use this information at your own risk. All mentions are cited. Educational purposes only.A transcutaneous electrical nerve stimulation (TENS) device is typically used to relieve the pain. Existing TENS devices consist of a hard-coded program and are not always customizable. My goal is to use an Arduino to make them programmable and handy. Arduino can be programmed to produce an electrical pulse pattern desired by the user. . Results indicate that Arduino can generate electrical pulses similar to existing TENS devices and can be easily changed if required. Thus, it provides customized treatment patterns and is portable.

To Build this Tens unit, you will first need to buy a 555 timer IC . The 555 timer is very small about a quarter of the size of your fingernail.

There are 2 types of Tens machine. High-Frequency Tens uses frequencies in the range of 80 to 100 Hz. This blocks the pain impulses going to the brain .

Low-frequency Tens uses frequencies from 2 to 4 Hz . This will help the body produce its own endorphins and increase local blood flow to relieve pain ( this can last for hours ) .

Square waves are universally encountered in digital switching circuits and are naturally generated by binary (two-level) logic devices. They are used as timing references or "clock signals", because their fast transitions are suitable for triggering synchronous logic circuits at precisely determined intervals. However, as the frequency-domain graph shows, square waves contain a wide range of harmonics.

Keywords

Arduino, Electrical pulse pattern, Pain relief, Transcutaneous electrical nerve stimulation (TENS).

1. Introduction

A transcutaneous electrical nerve stimulation (TENS) device is usually used to relieve pain through electrical pulse injections into our nerve system [11]. TENS devices available in the market use wires over long distances and hard-coded electrical pulse programs. Wired TENS devices assist users only in problems requiring limited movement. On the contrary, a programmable electrical pulse generator can help the user customize treatment patterns pharmacological and techniques [5].

The architecture of current TENS device circuits is mostly complex and uses many components to produce pulse width modulation (PWM) signals to generate electrical pulses. Thus, the objectives of this work are 1) to develop a simpler TENS circuit by using a programmable Arduino that can help the user deal with related nerve pain problems and relax muscles and 2) to develop an application for smartphones to make the TENS circuit be controlled remotely.

2.Development

Arduino Uno is one of the various Arduino microcontroller boards. This board comes with six inputs of analog, 14 digital input or output (I/O) pins (they can be utilized for PWM generation), a 16 MHz ceramic resonator, a USB connector, a force jack, an in-circuit serial programming header, and a reset

button [12]. It contains all that is expected to help the microcontroller; essentially, it is interfaced with a USB connection to a PC or started using an AC-to- DC connector or battery. The Arduino Uno is based on an Atmel 8-bit AVR microcontroller that was created in Trondheim, Norway in 1996. Most Arduino architectures are considered reduced-instruction-set computing and consume minimal computational time. An Arduino board has mixed fragments to support programming, and it can be segmented into various circuits. Numerous shields can be adjusted separately by allowing them to be stacked and used equally.

The Arduino board reveals most I/O pins for use via different microcontrollers . The Arduino Nano, Arduino-good No frills Board, and Boarduno sheets can provide male header pins to connect to solderless breadboards at the board’s underside. They produce PWM signals that replace the integrated circuits of the 555 and 7555 timers used in standard TENS devices. Arduino encoding can be performed through Arduino software to generate PWM signals. Arduino software is used to connect among TENS devices, and the PWM generator circuit is a common technique used to change the pulse width of signals. PWM has many applications, such as servo and speed control, effectively limiting motor and LED power. It is a square wave with different high and low times.

The Arduino Uno is used to replace the PWM generator circuit in this work, and the PWM output is obtained from Pin 3. Digital control is utilized in the PWM generation to make a square wave and a signal shared between on and off. The on-off example can recreate voltages in the full middle on (5 V) and off (0 V) by changing the amount of time the sign invests in versus the energy it spends off. The pulse width is known as the “on-time” length. It can be regulated to obtain analog qualities that fluctuate. When the on-off pattern is repeated rapidly, it will produce a steady-voltage output signal.

TENS circuit

The TENS circuit in this work is simpler than the existing circuit suggested in because some components have been replaced with the Arduino Uno to produce the PWM signal. The frequency and width of the pulse can be adjusted and controlled in accordance with the desired pattern. The circuit is supplied using a 9 V battery, as depicted in Figure 3. All essential devices in the TENS circuit are discussed in the following subsections.

2.1.1 Interface switch

A switch is required to interface between the low- voltage circuit from the Arduino Uno and the high- voltage TENS circuit. The most widely recognized type of switch is an electromechanical device that is physically worked with various electrical contacts associated with outer circuits. System activating the progress between two states can be either a “toggle” (flip switch for nonstop “on” or “off”) or “momentary” (push-for “on” or push-for “off”) type. An electronic switch is a device that switches an electrical circuit, intruding on the current or transmitting it from one conductor to another. The IRF9640 metal oxide semiconductor field effect transistor (MOSFET) that produces low power output is recommended over ordinary transistors. MOSFET is a transistor utilized for switching and intensifying electronic signs. Although MOSFET is a four- terminal device with gate, source, drain, and body terminals, its body is frequently linked to the source terminal, making it a three-terminal device similar to any other field-impact device transistors. Two terminals are typically connected to each other (short- circuited) inside, given three terminals that turn out in electrical diagrams.

MOSFET can be considered the most successive transistor in digital and analog circuits [16]. In the enhancement mode, the MOSFET voltage drop over the oxide convinces a conducting channel between the source and channel reaching the field. The expression “enhancement mode” alludes to the increase in conductivity with the increment in the oxide field that inputs carriers to the channel alluded to as the inversion layer. The channel comprises bearers in a surface impurity layer of the inverse type to the substrate, and conductivity is diminished using a field of channel bearers from this surface layer.

2.1.2 Voltage regulator

This circuit consists of a capacitor to regulate voltage from the supplied 9 V battery. The capacitor comprises of two aloof electrical terminals used to charge energy in an electrical field electrostatically. Aluminum thin films may be used as conductors. Capacitors are widely used in standard electronic devices. A non-conductive dielectric acts to increase the charge limit of the condenser. A condenser does not disseminate energy; instead, it stores energy among its plates as an electrostatic field. A capacitor provides a sifting activity by parting with a path from the load for the harmonic current.

The capacitor is also used to shorten overshoot and swell voltage at the step-down converter output. With the lack of capacity and high equivalent series resistance (ESR) at the output capacitor, enormous overshoot grounds are caused by the lack of output capacitance and substantial voltage swell . The wave content for a step-down converter circuit can be regulated by incorporating a capacitor with adequate capacitance and low ESR. 2.1.3Current limiter

A potentiometer controls the output current injected through the human skin. The resistance of the human skin depends on age and gender. A potentiometer is a physical three-terminal variable resistor. One terminal interface moves over the resistive part with a sliding touch called a wiper, and the other ends of a resistive component are connected by two terminals. The resistive component can be regarded as a series of two resistors (potentiometer resistance), in which the position of the wiper determines the resistance ratio of the primary resistor to the subsequent resistor. The potentiometer output voltage can be determined using the wiper. The potentiometer essentially works as a voltage divider to vary the voltage at terminals. As a result, the current flow through the human body can be controlled to prevent inconvenience. The potentiometer is known as a “potmeter” or “pot”. The most popular type of potentiometer is the single-turn rotation. This sort of potentiometer usually utilizes sound volume control, similar to different applications. It is generally made of cermet, metal film, wire wound, carbon composition, and conductive plastic.

2.1.4 Step-up transformer

A transformer boosts the voltage from the supplied 9 V battery to a higher voltage at skin terminals. Large windings are connected to probes and earth through a resistor. In this case, the output voltage can reach a maximum of ±60 V electrical pulses by using a transformer with 1:10 ratio.

3. Results

The proposed TENS circuit based on the Arduino Uno board can produce output specifications based on the standard circuit. A monophasic pulse waveform is generated because the PWM signal is used in the proposed circuit. The pulse amplitude can be adjusted by using a digital potentiometer in the circuit. Therefore, a pulse current amplitude similar to the standard [21] is produced. The pulse frequency can be obtained from the time period of the output PWM signal. The period is measured at 0.008 s or equivalent to 125 Hz. From the signal, the pulse duration is provided by the “on” time. It is measured at 100 μs. This finding clearly shows that the proposed TENS produces the output waveform in accordance with the standard.

This work successfully demonstrates that the TENS circuit can be developed using Arduino board and controlled remotely using a smartphone. For safety precautions, the entire system is carried out within a simulation environment. Hence, the physical effects on its operation are not considered. The actual dimension and weight of the TENS device also cannot be determined. Nevertheless, the capability of the TENS device for a real-time application can be investigated using Tinkercad.

4. Conclusion and future works

Pain can be treated through high-frequency TENS which should be used as an adjunct to pharmacologic methods to replace pills. This paper presents a TENS circuit based on a programmable Arduino. Nearly half of the components in the original TENS circuit can be replaced with the Arduino Uno. Then, an application is developed using the MIT App Inventor platform to remotely control the electrical pulses from the TENS circuit during treatment using a smartphone. The results show that the proposed TENS circuit can produce similar electrical pulses to those by using the standard TENS device. The smartphone application enables remotely controlling the TENS device. In future works, the proposed TENS device can be developed using hardware, and the optimal dimension of the device can be obtained. As a result, the conventional TENS device can be improved to avoid the hassle of wires and become highly flexible in terms of treatment patterns.

Acknowledgment

References

1. [1]  Raja SN, Carr DB, Cohen M, Finnerup NB, Flor H, Gibson S, et al. The revised international association for the study of pain definition of pain: concepts, challenges, and compromises. Pain. 2020; 161(9):1976-82.

2. [2]  Radhakrishnan R, Sluka KA. Deep tissue afferents, but not cutaneous afferents, mediate transcutaneous electrical nerve Stimulation–Induced antihyperalgesia. The Journal of Pain. 2005; 6(10):673-80.

[3]  Farrell SM, Green A, Aziz T. The current state of deep brain stimulation for chronic pain and its context in other forms of neuromodulation. Brain Sciences. 2018; 8(8):1-19.

1. [4]  MokhtariT,RenQ,LiN,WangF,BiY,HuL. Transcutaneous electrical nerve stimulation in relieving neuropathic pain: basic mechanisms and clinical applications. Current Pain and Headache Reports. 2020; 24(4):1-4.

2. [5]  Sabino GS, Santos CM, Francischi JN, De Resende MA. Release of endogenous opioids following transcutaneous electric nerve stimulation in an experimental model of acute inflammatory pain. The Journal of Pain. 2008; 9(2):157-63.

3. [6]  Adewumi AD, Staatz CE, Hollingworth SA, Connor JP, Alati R. Prescription opioid fatalities: examining why the healer could be the culprit. Drug Safety. 2018; 41(11):1023-33.

4. [7]  DeSantana JM, Walsh DM, Vance C, Rakel BA, Sluka KA. Effectiveness of transcutaneous electrical nerve stimulation for treatment of hyperalgesia and pain. Current Rheumatology Reports. 2008; 10(6):492-9.

5. [8]  Dailey DL, Rakel BA, Vance CG, Liebano RE, Amrit AS, Bush HM, et al. Transcutaneous electrical nerve stimulation reduces pain, fatigue and hyperalgesia while restoring central inhibition in primary fibromyalgia. Pain. 2013; 154(11):2554-62.

6. [9]  Sluka KA, Vance CG, Lisi TL. High‐frequency, but not low‐frequency, transcutaneous electrical nerve stimulation reduces aspartate and glutamate release in the spinal cord dorsal horn. Journal of Neurochemistry. 2005; 95(6):1794-801.

7. [10]  Rajkumar SV. The high cost of prescription drugs: causes and solutions. 2020; 10:1-5.

[11] Johnson M. Transcutaneous electrical nerve stimulation: mechanisms, clinical application and evidence. Reviews in pain. 2007; 1(1):7-11.

1. [12]  Hidayanti F, Rahmah F, Wiryawan A. Design of motorcycle security system with fingerprint sensor using arduino uno microcontroller. International Journal of Advanced Science and Technology. 2020; 29(05):4374-91.

2. [13]  Bestley Joe S, Ramadevi R, Rani VA, Rajalakshmi G. Automatic cooking machine using arduino. International Journal of Emerging Trends in Engineering Research. 2020; 8(1):35-40.

3. [14]  Haque MR, Jaman S, Saklayen MG, Khondoker MM, Siddik AB, Sara U, et al. Towards the development of an energy-efficient smart home through IoT. International Journal of Advanced Technology and Engineering Exploration. 2019; 6(58):208-16.

4. [15]  Shirafkan R, Shoaei O, Ahmadi MK. A high efficient adiabatic Transcutaneous Electrical Nerve Stimulator (TENS) with current regulation. AEU-International Journal of Electronics and Communications. 2020; 123:1-24.

5. [16]  Sharma SM, Singh A, Dasgupta S, Kartikeyan MV. A review on the compact modeling of parasitic capacitance: from basic to advanced FETs. Journal of Computational Electronics. 2020; 19(3):1116-25.

17] Zhang H, Huang Q, Wang H, Shi X. Efficient method to investigate the equivalent series resistance of a capacitor in low frequency range. IET Science, Measurement & Technology. 2020; 14(4):494-8.

[18] Kortman HG, Wilder SC, Geisbush TR, Narayanaswami P, Rutkove SB. Age-and gender- associated differences in electrical impedance values of skeletal muscle. Physiological Measurement. 2013; 34(12): 1611-

[19] Africa AD, Ching G, Go K, Evidente R, Uy J. A comprehensive study on application development software systems. International Journal of Emerging Trends in Engineering Research. 2019; 7(8):99-103.

[20] Kumar A, Nirosha T. Home security using embedded platform–an experimental validation. IOSR Journal of Electronics and Communication Engineering. 2020; 15(2):12-17.

[21] Tashani O, Johnson MI. Transcutaneous electrical nerve stimulation (TENS) a possible aid for pain relief in developing countries? Libyan Journal of Medicine. 2008; 4(2):62-5.