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Proposal: Usability Testing of TENS Unit




November 4, 2019

Johnson (2007) describes the TENS unit as a small, battery controlled device with leads linked to sticky pads known as the electrodes. TENS are meant for helping people that are prone to chronic pains; for instance, people suffering from neuropathic pain, Fibromyalgia, arthritis and joint pains, muscle pains as well as back and neck pains. This study aims at evaluating and testing of TENS Unit and its usability. The study will help identify the usability of the device and any modifications required before the summative testing.
This protocol is written as per the following standard
• FDA Final Guidance for Industry and FDA staff: Design Applying Human Factors and usability Engineering to Optimize Medical Device Design (February 3, 2016)
• ANS/AAMI HE75:2015
• FDA Final Guidance for Industry and FDA staff: Design Consideration for Devices intended for Home Use (August 5, 2014)
• IEC 62366-1:2015
2.0 Description of the intended device users, uses, use environments and training
2.1 intended Users
The intended users of the TENS device include;
• Patients who suffer from pain resulting from periods for women, labor pains, postoperative pain, joint, back, and neck pain. It is also used by patients suffering from conditions such as endometriosis, arthritis, and multiple sclerosis.
• Caregivers who have experience in taking care of patients suffering from conditions such as arthritis, endometriosis, and multiple sclerosis.
• Health professionals such as doctors and nurses help to treat pain caused by conditions such as fibromyalgia, arthritis spinal cord injury, and endometriosis.
2.2 intended uses
TENS is used to help reduce pain and muscle spasms caused by conditions such as arthritis, period pains, back, and neck and knee pain, pelvic pain caused by endometriosis. It is sometimes used to relieve pain during labor. It has controls that allow people to administer the required level of pain relief.
2.3 use environment
TENS devise is intended for use at home, or clinical setting or any other situation where there are patients, caregivers, and additional health expertise. The real-life application of the TENS machine may vary in ways that impact the user’s ability to safely and effectively use the tool. The following are some of the environment variables that affect the safe and effective use of the TENS device.
Users should make use of the TENS machine in the right environment setting. Proper maintenance of the device should be observed to ensure the adequate performance of the invention.
2.4 Training
The patients, caregivers and health professionals need to be trained before they are allocated the device. During training, the trainer gives a brief description of the equipment and how it is used. A precise tutorial is also offered to help the patents remember how to use the device while at home. The training targets mainly the untrained personnel to help improve their skills of using the device.
3.0 Description of Device user interface
TENS is a device that is compact and lightweight, battery-operated that is based on solid-state circuitry and user-friendly system.

3.1 Auto-injector device machine
TENS is mostly delivered from small, battery-powered devices. TENS digital machines are becoming more widely available with extra features, for instance, the automated frequency sweeps and more complex stimulation patterns. The current intensity of the TENS machine ranges from 0 to 80 mA. The current may seem small, but it is sufficient because the primary target for the therapy is the sensory nerve. So long as enough flow is passed through the tissues to depolarize the nerves, the modality is operative. The machine delivers discrete pulses of electric energy at the rate of delivery of those pulses which vary from 1 to 2 pulses per second. TENS machines offer a dual channel output- two pairs of electrodes that are used simultaneously. The pulses delivered by the TENS stimulators vary between manufacturers but are also asymmetrical biphasic modifies square wave pulses. The machine has a pair of electrode means for making surface contact and supplying electrical current to the mammalian tissue. The electrical circuit means for providing to the pair of electrode means from microamps up to about 900 microcaps of the monophasic sequence of the burst of a D.C. carrier signal.

3.2 Summary of the operating sequence
TENS machines deliver small electrical pulses to the body through electrodes placed on the skin. Pain signals reach the brain’s vial nerves and the spinal cord. To ensure successful use of the machine, the user should;
• Ensure the machine is switched off before placing the electrode pads on the skin.
• Hold the pads between your fingers and carefully turn the machine on to test it. One should feel a tickling sensation.
• Ensure the skin where the pads are placed is dry and clean. There should be no cuts, scratches, or skin irritation.
• The pads should be placed on either side of the pain. Use Self-adhesive pads or flexible rubber pad, which need to be fully covered on the surface to be applied to the skin using a reedy coating of conductive gel.
• If you intend to move around, fix the pads to the skin, and set the required pulse rate setting.
• Switch on the machine slowly until you feel a tingling sensation. It should be firm but not uncomfortable. The feeling will begin to drop away slowly after some time. Turn up the machine and slightly and leave it in the remaining time in use. Ensure there is no muscle contraction to avoid worsening the pain.
• Turn the machine off and disconnect the electrodes from the machine when the session ends.
• The device should be used for not less than 45 minutes. It can, however, be used for up to 12 hours before cleaning and re-siting the electrodes. Remove the pad from the skin and clean it after using the machine. Use regular soap and water when cleaning the surface. If there is any irritation accruing from the pads, use a different skin area the next time you are using the machine.
• The self-adhesive type of pads should not be washed. However, if you use the rubber pad, you can clean off the conducting gel with mild soap and water then rinse them appropriately.
4. Analysis of hazards associated with the use of the device
The influencer undertook a comprehensive task to analyze the use of the devise to help identify effects of the devise on the patient. The table below shows the harm description of severity by risk type and the ranking.
Severity ratings
Severity classification harm severity description by risk type severity ranking
Catastrophic leads to death of the patient 3
Critical result in severe damage of the skin 2
Serious Couse injuries requiring professional medical attention 3
Minor Couse injuries which do not require professional medical 2
Negligible result to discomfort on the patient 1

5.0. Description and categorization of the critical task and essential task
The table below analyzes various types of TENS, multiple tasks they perform and the patient experience

6.0 Details of Human Factors in Formative Testing
6.1 Overall Study Approach
This part will involve a feign study whereby members will relate with the device to assess its usability and also the main features of the TENS device. The study will include a testing session in which the organizer will give the participants, representing impending users a specific task to execute. They will handle all questions related to the use of the device. The organizer will show the sample behavior and response. The tasks undertaken will help to exhibit the patient’s behavior and reaction in real-life situations.
6.2. Study Timeframe
The study will be steered at Scape House in Illinois.
6.3. Study Reporting
The reporting of the study will be as per the FA’s Final Guideline: Applying Human Factors and Usability Engineering to Medical devices issued in February 2016, the IEC 62366-2015. The reporter will also include a summary of the study results and safety outcomes that are similar to the task.
6.4. Risk classification
The study will be very genuine, but the patients will not use real medication. The participants will test their skills basing on how they relate to the device. Based on the pertinent FDA, the study does not have any dangers to the study participants because they are not designed for use in sustaining human life and are also not meant for the creation of problems when using the device.
6.5. Study Participants
6.5.1 Number, Type and Rationale
The study will entail seven participants per age group. The ages will be divided in terms of decades from 45 to 85 years to represent the larger group of the intended users. We will also include professionals, such as nurses and caregivers.
Table; User group details
group No participants Training
status No of sessions Characteristics
The caregivers 16 untrained 1 • The age was older than 21 years
• They were not trained, hence nonprofessionals
• They are not experienced to the use of the device
Nurses 22 Untrained 1 • They are medical professional who they are required and expected to handle the device
• They are willing to attend more than an hour session
• Experienced have experienced chronic pains in patients
Chronic pain patients 12 untrained 1 • they are not experienced caregivers
• they should be willing to participate more than hours session
• the should be patients suffering neuropathic pain or extreme pain

6.5.2 Duration and users’ participation
Involvement in the study assessment begins when the participants sign an Informed Consent Form and end when they have completed the whole session. For each session, the duration shall not be more than one hour. Participants who arrive late shall not be punished but will have to undertake the study in the next group. If they choose not to proceed with the test, they will have to exit the study earlier, and the data collected during the withdrawal period may or may not be used, depending on the reason for withdrawal.
6.6. Study Devices and Material
The TENS device used in the study will not be real. The participants will use a fake TENS device that can fit the compartments. Other materials provide for the study include pens, notebooks, wet wipes, and gauze pads.
6.8. Study environment
It will include a home environment for the elderly and the caregivers. They will use a large and well-ventilated room with furniture. Clinical environment whereby the health professionals will use the device in a clinical replicated environment such us the hospital ward.
6.8.2 Study Locations
It will be carried out at Joe Dumas’s Fieldhouse in Detroit, MI
6.9 Study Team and Data Recording
All the teams will have a senior human factor expert in charge of the study session. A data analyst will be available to manage video recording and provide assistance to that organizer where necessary. The information will be collected by recording all the observations and the participants’ responses to the interview. The data analyst will ensure that all the data is captured and analyzed on a spreadsheet.
6.10 Data collection and analysis
The participants will be allowed to use the device for the first time without any medical assistance from the organizer. The organizer will then ask for the participants’ feedback on the device, their ratings, and expectations. The facilitator will examine the participants to understand their choices. They will also be asked open-ended questions to identify if they faced any problems when using the device and during the whole session.
7.0. Results and Findings
Transcutaneous Electrical Nerve Stimulation (TENS) units are electronic medical devices that are used for the treatment of acute muscle pain. The devices work through sending electrical pulses that are delivered through the electrodes that have ends fitted with adhesive pads that make contact with a person’s skin. The working principle of this device is that when pulses are passed through the nerves, it triggers the brain to start producing substances such as endorphins that help as a pain relief hormone. Often TENS units are used for short-term or temporary pain relief. TENS are meant for helping people that are prone to chronic pains; for instance, people suffering from neuropathic pain, Fibromyalgia, arthritis and joint pains, muscle pains as well as back and neck pains. Previous studies on TENS have revealed that they achieve the highest level of effectiveness when used when a person is active and for not less than 30 minutes. TENS were found to be less effective when used when the person is in an inactive or stationary state such us when resting or lying. As such, TENS are recommended for use during active body activity sessions, such as when exercising or when walking. There is no consensus about the effectiveness of TENS devices in the treatment of pain (Gladwell, Et al. 2016).
8.0. Recommendations
Although the device appears to be perfect and ready for use by health professionals and patients, the company can make some significant advances to make it more effective and efficient during usage. The companies should modify the device so that the patient experiences less tingling and buzzing. The companies should plan and provide a rechargeable battery for the TENS device, which is cheaper compared to buying a new battery.
9.0 Conclusion
The TENS unit is mainly used to relieve pain for conditions such as arthritis. Using the device, however, has generated volatile results because of the lack of high-quality scientific studies and clinical trials. TENS device can relieve depending on factors lie the affected area of the boy and the medication intensity. Having an idea of how these factors impact the TENS can assist people in using the device appropriately. Most people use the TENS unit safely, while others experience side effects. The patient should consult the doctor before opting for TENS as an alternative treatment or combining with other ways of managing pain.

7.0 Appendix –Interview Guide
Date _________ Time_____________ Participant_____________

I appreciate your attendance to our session and remind you to sign the consent paper. Also I would like to know if anyone of you have questions to challenge the document or to add on it.
• I would like to make clear that by signing the document you are part of it and only permitted to start and see how it function.
• By signing the document, you are given the permission to record videos and audios but not taken to social media or made public.
• You are permitted to study the document and make recommendation.
7.1 Background Questions
1 Have you ever experienced the device which works same as medical usability device
{} yes {} No
2 What was the most interesting part of the device
{} operations
{} the price
3 To confirm are you a_____
[] nurse
[] physician
[] physician assistant
[] medical engineer
4 Gender _______
[] male [ ] female
5 How old are you
Record age ______________
6 Are you right handed, left handed or both
[] right [] left [ ] Both
7 Do you have any physical disability?
[] yes [ ] No
If yes state, the ailment__________________
8 Are you a resident of United States
[] yes [ ] No
9 Have you in anyway involved in any related market research of TSM
[ ] Yes [ ] No
10 Which of the following diseases does the patient suffer from
[ ] back pain
[ ] neuropathic pain
[ ] fibromyalgia
[ ] arthritis
[ ] back pains
[ ] muscle pains
11 Which category do you fall in?
[ ] patient
[ ] health professional
[ ] caregiver
12 Will the device solve the pain related issues in patients completely?
[ ] Yes
[ ] No
13 Rate the device from other related medical devices on scale of 1-10
0-3 good [ ]
3-6 better [ ]
7-8 good [ ]
9-10 best [ ]

Gibson, W., Wand, B. M., Meads, C., Catley, M. J., & O’Connell, N. E. (2019). Transcutaneous electrical nerve stimulation (TENS) for chronic pain – an overview of Cochrane Reviews. The Cochrane database of systematic reviews, 4(4), CD011890. doi:10.1002/14651858.CD011890.pub3
Johnson M. (2007). Transcutaneous Electrical Nerve Stimulation: Mechanisms, Clinical Application and Evidence. Reviews in pain, 1(1), 7–11. doi:10.1177/204946370700100103
Kennedy J, Roll JM, Schraudner T, Murphy S, McPherson S. Prevalence of persistent pain in the U.S. adult population: new data from the 2010 national health interview survey. Journal of Pain 2014;15(10):979‐84.
Marcus, E. (2011). Design, User Experience, and Usability. Theory, Methods, Tools and Practice. First International Conference, DUXU 2011, Held as Part of HCI International 2011, Orlando, FL, USA, July 9-14, 2011, Proceedings, Part I
Gladwell, P.M., Badlan, K., Cramp, F., Palmer, S. (2016). Problems, Solutions, and Strategies Reported by Users of Transcutaneous Electrical Nerve Stimulation for Chronic Musculoskeletal Pain: Qualitative Exploration Using Patient Interviews, Physical Therapy, Volume 96, Issue 7, pp 1039–1048,
Tripathi, J. & Sethi, S. (2017). Use of Transcutaneous Nerve Stimulator (TENS) for localized Pain relief – A REVIEW. International Journal on Recent and Innovation Trends in Computing and Communication. 5(5); 707 – 710


Inciteprofessor is a Master Holder in Actuarial Science from the World's Best Universities. He also possesses a Bachelor degree in Computer Science and Cyber Security. He has worked with many freelance companies including Freelancers, Fiverr , Studybay, Essayshark, Essaywriters, Writerbay, Edusson, and Chegg Tutor. He offers help in research paper writing & tutoring in Mathematics, Finance, and Computer Science field.

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