zewa 21021 User Manual Download Page 1

1  FOREWORD

1.1 Introduction

The device 21021 is a single output channel Mini TENS&EMS device. Before 

using, please read all the instructions in this user manual carefully and keep it safe 

for future.

Mini TENS&EMS device belongs to the group of electrical stimulation systems. It 

has two basic function – TENS (Transcutaneous Electrical Nerve Stimulation) and 

EMS (Electronic Muscle Stimulation).

Function of the Mini TENS&EMS device: The device has 5 application programs 

(3 TENS programs and 2 EMS programs) and applies electric currents in the low-

frequency range for therapy. The respective application program controls the 

generated electric impulses, their intensity, frequency and frequency range. The 

values for the respective program are listed on pa

rt

 

7

The operation principle of electrical stimulation equipment is based on simulating 

the body’s own pulses which are transcutaneously transmitted to nerve or muscle 

fibers by means of electrode. The intensity of the single channel can be adjusted 

separately and can be applied individually to one body region. The device has 

single channel and one butterfly-shaped electrode, which allows you to stimulate 

one muscle groups simultaneously with a large selection of standard programs. 

The electrical pulse is transmitted to the tissue, then affect the transmission of 

stimulation in nerve conduction as well as the Neuron and muscle tissue in the 

field of application part.

1.2 Medical background
1.2.1 EXPLANATION OF PAIN 

Pain is a warning system and the body’s method of reminding us that something 

is wrong. Pain is important signal; without it abnormal conditions may go 

undetected, causing damage or injury to vital parts of our bodies. Even though 

pain is a necessary warning signal of trauma or malfunction in the body, nature 

may have gone too far in its design.

This manual is valid for the 21021 Stimulator

Be sure to read this instruction manual before operation and keep properly.

This user manual is published by 

Zewa Inc

  

Zewa Inc 

does not guarantee its contents and reserves the right to 

improve and amend it at any time without prior notice. Amendments will however be 

published in a new edition of this manual.

All Rights Reserved.

21021

 Rev. V1.0© 2014-

Zewa

, printed in 

June, 26,2014

Mini TEN&EMS Device

USER MANUAL

(For OTC PURPOSE)

Aside from its value in diagnosis, long-lasting persistent pain serves useless 

purpose. Pain does not begin until coded message travels to the brain where 

it is decoded, analyzed, and then reacted to. The pain message travels from the 

injured area along the small nerves leading to the spinal cord. Here the message 

is switched to different nerves that travel up the spinal cord to the brain. The pain 

message is then interpreted, referred back and the pain is felt.

1.2.2 EXPLANATION OF TENS?

TENS (Transcutaneous Electrical Nerve Stimulation) gives good results in relief of 

pain. It is clinically proven and used daily by physiotherapists, other caregivers and 

top athletes around the world. High-frequency TENS activates the pain-inhibiting 

mechanisms of the nervous system. Electrical impulses from electrodes, placed 

on the skin over or near the painful area, stimulate the nerves to block the pain 

signals to the brain, and the pain is not perceived. Low-frequency TENS stimulates 

the release of endorphins, the body’s natural painkillers. 

1.2.3 EXPLANATION OF EMS 

Electrical Muscle Stimulation is an internationally accepted and proven way of 

treating muscular injuries. It works by sending electronic pulses to the muscle 

needing treatment; that causes the muscle to exercise passively. It is a product 

derived from the square waveform, originally invented by John Faraday in 1831. 

Through the square wave pattern it is able to work directly on muscle motor 

neurons. The Ultra EMS System has low frequency and this in conjunction with the 

square wave pattern allows direct work on muscle groupings.

2  SAFETY INFORMATION

2.1 Intended use
For program N1, B and H of TENS mode

To be used for temporary relief of pain associated with sore and aching muscles 

due to strain from exercise or normal household work activities.

For program E1 and E2 of EMS mode

To be used to stimulate healthy muscles in order to improve and facilitate muscle 

performance.

2.2 Contraindications

1)  Do not use this device if you have a cardiac pacemaker, implanted defibrillator, 

or other implanted metallic or electronic device. Such use could cause electric 
shock, burns, electrical interference, or death.

2)  The device should not be used when cancerous lesions or other lesions are 

present in the treatment area.

3)  Stimulation should not be applied over swollen, infected, inflamed areas or 

skin eruptions (e.g. phlebitis, thrombophlebitis, varicose veins, etc.). 

4)  Electrode placements must be avoided that apply current to the carotid sinus 

region (anterior neck) or transcerebrally (through the head).

5)  This device should not be used over poorly enervated areas.
6)  Inguinal hernia
7)  Do not use on scarred areas following surgery for at least 10 months after the 

operation

8)  Do not use with serious arterial circulatory problems in the lower limbs

2.3 Warning    

1)    If you have had medical or physical treatment for your pain, consult with your 

physician before using this device.

2)   If your pain does not improve, becomes more than mild, or continues for more 

than five days, stop using the device and consult with your physician.

3)   Do not apply stimulation over your neck or mouth because this could 

cause severe muscle spasms resulting in closure of your airway, difficulty in 
breathing, or adverse effects on heart rhythm or blood pressure.

4)  Do not apply stimulation across your chest because the introduction of 

electrical current into the chest may cause rhythm disturbances to your 
heart, which could be lethal.

5)    Do not apply stimulation over, or in proximity to, cancerous lesions.
6)    Do not apply stimulation in the presence of electronic monitoring equipment 

(e.g., cardiac monitors, ECG alarms), which may not operate properly when 
electrical stimulation device is in use.

7)    Do not apply stimulation when in the bath or shower.
8)    Do not apply stimulation while sleeping.
9)   Do not apply stimulation while driving, operating machinery, or during any 

activity in which electrical stimulation can put your at risk of injury; and

10)  Apply stimulation only to normal, intact, clean, healthy skin.
11)  The long-term effects electrical stimulation are unknown. Electrical stimulation 

device do not have any curative value.

12) Stimulation should not be applied transthoracically in that the introduction of 

electrical current into the heart may cause cardiac arrhythmias.

13)  Stimulation should not take place while the user is connected to high-

frequency surgical equipment, that may cause burn injuries on the skin 
under the electrodes, as well as problems with the stimulator.

14)  Do not use the stimulator in the vicinity of shortwave or microwave therapy 

equipment, since this may affect the output power of the stimulator.

15)  Never use near the heat. Stimulation electrodes should never be placed 

anywhere on the front of the thorax (marked by ribs and breastbone), but 
above all not on the two large pectoral muscles. Here it can increase the risk 

of ventricular fibrillation and lead to cardiac arrest.

16)  Never use on the eye area.
17)  Never use near the genitals.
18)  Never use on the areas of the skin which lack normal sensation
19)  Keep electrodes separate during treatment, electrode in contact with other 

could result in improper stimulation or skin burns.

20)  Keep the stimulator out of reach of children.
21)  Consult your doctor if you are in any doubt whatsoever.
22) Discontinue and do not increase the intensity level if you feel discomfort 

during use.

2.4 Precautions

1)    TENS is not effective for pain of central origin including headache.
2)   TENS is not a substitute for pain medications and other pain management 

therapies.

3)     TENS devices have no curative value.
4)   TENS is a symptomatic treatment and, as such, suppresses the sensation of 

pain that would otherwise serve as a protective mechanism.

5)   Effectiveness is highly dependent upon patient selection by a practitioner 

qualified in the management of pain patients.

6)     The long-term effects of electrical stimulation are unknown.
7)   Since the effects of stimulation of the brain are unknown, stimulation should 

not be applied across your head, and electrodes should not be placed on 
opposite sides of your head.

8)     The safety of electrical stimulation during pregnancy has not been 

established.

9)    You may experience skin irritation or hypersensitivity due to the electrical 

stimulation or electrical conductive medium (silica gel).

10)  If you have suspected or diagnosed heart disease, you should follow 

precautions recommended by your physician,                                                        

11)  If you have suspected or diagnosed epilepsy, you should follow precautions 

recommended by your physician.

12) Use caution if you have a tendency to bleed internally, such as following an 

injury of fracture.

13)  Consult with your physician prior to using the device after a recent surgical 

procedure, because stimulation may disrupt the healing process.

14)  Use caution if stimulation is applied over the menstruation or pregnant 

uterus; and 

15)  Use caution if stimulation is applied over areas of skin that lack normal 

sensation.

16)  For single patient use only.                                    
17)  Keep yourself informed of the contraindications.
18)  This stimulator is never use by patients who have noncompliant, emotionally 

disturbed, dementia, or low IQ.

19)  The instruction of use was listed, any improper use may be dangerous.
20)  Caution should be used for patients with suspected or diagnosed heart 

problems.

21)  Isolated cases of skin irritation may occur at the site of the electrode 

placement following long-term application.

22)  Do not use this device at the same time as other equipment which sends 

electrical pulses to your body.

23)  Do not use sharp objects such as pencil point or ballpoint pen to operate the 

buttons on the control panel.

24)  To check the electrode connections before each use.
25)  This device should be used only with the electrodes recommended for use 

by the manufacturer.

2.5 Adverse Reactions

1)  Possible skin irritation or electrode burn under the electrodes may occur.
2)  On very rare occasions, first-time users of EMS have reported feeling light-

headed or faint. We recommend that you use the product while seated until 
you become accustomed to the sensation.

3)  If the stimulation levels are uncomfortable or become uncomfortable, reduce 

the stimulation Intensity to a comfortable level and contact your physician if 
problems persist.

3  GETTING TO KNOW YOUR DEVICE

3.1 Front Rear Panel

1) [ON /SET+] button

2) Program name

3) [OFF /SET-] button 

4) Electrode buttons

5) Battery compartment 

6) Tape for removing battery

7) Batter cover

 

3.2 Key Functions 
[ON/SET+] Button 

In standby state: turn on the device; in treatment state: to increase the output 

intensity. 

[OFF/SET-] Button 

In power on state: press the button to select the treatment program; keep press 

the button to 2 seconds to turn off the device; in treatment state: to decrease the 

output intensity.

3.3 Accessories

No.

Description

Part No.

QTY

1

Pain Relief Plaster

ED405

1 pc

2

Self-adhesive Electrodes (28x 53 

mm, Butterfly-shaped)

AC-EP2853U

1 pc

3

Ordinary batteries (1.5V, AAA)

AC-1UAAAC

2 pcs

4

User manual

/

1 pc

4 SPECIFICATION

4.1Technical information

Device name

Multi-function TENS&EMS Device

Model/type
Power supply

3V d.c., 2x AAA batteries

Output Channel

Single channel

Wave sharp

Bi-phase square-wave pulse

Output voltage

Max. 35Vpp (at 500ohm load)

Output current

Max. 70mA (at 500ohm load)

Treatment time

30min

Output intensity

0 to 10 levels, adjustable

Number of program

5 programs: N, B, H, E1 and E2

Treatment mode:

TENS and EMS mode

Operating conditions

5°C to 40°C with a relative humidity of 30%-

85%, atmospheric pressure from 700 hPa to 

1060 hPa

Storage conditions

-10°C to 50°C with a relative humidity of 

10%-90%, atmospheric pressure  

from 700 hPa to 1060 hPa

Less than 10uA (At power off mode)

Dormancy current

Less than 10uA (At power off mode)

Working current

Less than 50mA (At the N1 program)

Dimensions

57x45x16.5 mm

Weight

20g (without batteries) 42g (with batteries)

Automatic shutoff

3 minutes

Classification

BF type applied part, internal power 

equipment

Electrode detection function

The amplitude level will be reset to 0 V, 

when the amplitude level is 1 or greater 

and an open circuit at either channel is 

detected.

Size of electrodes pad

3" X 4"

, Butterfly-shaped

Output precision

All the output parameters allow ±20% error 

for the specification.

Technical specification 

P.W. (pulse width)

200, 250us

P.R. (Frequency)

2, 80Hz (Hz=vibration per second)

Burst frequency

2Hz

Output characteristics

Constant Voltage (CV)

Normal

The pulse rate and pulse width output will 

be constant based on the design value.

Han

2Hz/250us first output 3 sec. and then 

output 3 sec. 80Hz/200us.

5 OPERATING INSTRUCTION

5.1 Battery
5.1.1 Check/ replace batteries

Open the battery cover, insert two batteries 

(type AAA) into the battery compartment. Make 

sure you are installing the battery properly. Be 

sure to match the positive and negative ends 

of the battery to the markings in the battery 

compartment of device. 

BE SURE TO MATCH THE POSITIVE AND NEGATIVE ENDS OF THE 
BATTERY WITH THE MARKINGS IN THE BATTERY COMPARTMENT 
OF UNIT.

5.1.2 Disposal of battery

Spent batteries are not belong to the household waste. Dispose of 

the battery according to the current regulations. As a consumer, you 

have legal obligation to return spent battery to the Recycle Bin.

  Caution:

1. If a battery was swallowed please seek medical attention immediately!

2. In case of battery leakage, please avoid contacting the battery with skin, eyes 

and mucus membranes, once contacting leakage, please wash the contact 

part with plenty of clean water and contact your doctor immediately. 

3. Battery can not be dismantled, thrown into fire or short-circuited.

4. Protect battery from excess heat; Take the battery out of the product if they 

are spent or if you don’t use it for a long time. This can prevent device damage 

because of the battery leakage.

5. Replace all of the batteries simultaneously!

6. Always replace the device with same type battery.

5.2 Connect electrode to device

Before proceeding to this step, be sure the device is completely turned OFF.  

Connect the electrode to the electrode button of stimulator correctly. Please see 

following photos for the correction connecting method. 

  Caution:

Always use the electrode which is comply with the requirements of the IEC/

EN60601-1, ISO10993-1/-5/-10, such as the electrode with CE mark, or which are 

legally marketed in the US under 510(K) procedure.

5.3 Place electrodes on skin

Place the electrode on the part you need treatment, and base on the instructions 

of this user manual. Before use, please 

make the skin that need treatment and the 

silica gel of electrode clean and humid, to 

prevent the discomfort that cause by dry 

skin. Please ensure the skin and electrode 

connection well.

  Caution:

1. Please turn off to prevent electric shock when pre-moving the treatment 

position of the electrode.

2. Before applying the electrode, it is recommended to wash and degrease the 

skin, and then dry it.

3. Never remove the electrode from the skin while the stimulator is still treating.

4. Only use the electrodes that provided by the manufacturer, use other 

accessories could result in injury to the patient.

5.3.4 Electrode placement

FDES106 is a kind of OTC stimulator, suitable for home 

use, you only need to use according to the user manual, 

place the electrode on the position where you feel pain 

and need to exercise, treating and adjusting base on 

your own feeling.

The different programs with corresponding applicable 
symptoms as below:

Program No. Applicable disease symptoms Applicable Location Diagram

N

Shoulder pain

Arm pain

Elbow pain

4.  Low back pain

B

Shoulder pain

Arm pain

Elbow pain

4.  low back pain

 Same as N, but the stimulation 

is blander.

H

Shoulder pain

Arm pain

Elbow pain

4.  Low back pain

Same as N, but the stimulation 

strength is between N and B.

E1

Applicable for buttocks, thigh 

and leg:

improve and facilitate muscle 

performance.

E2

Applicable for hand, arm and 

abdomen:

improve and facilitate muscle 

performance.

6  INSTRUCTIONS FOR USE
6.1 Turn on

When use for the first time, open the battery cover and load two new batteries 

(Please kindly review item 5.1.1 for the operating steps and schematic diagram)

 Then press the [on/set+] button to turn the device on, and the default “N” 

program indicator LED will be lighting.

 

6.2 Select the application program

In the state of power on, press

off/ set -

to switch the current application pro-

gram. The LED indicator of corresponding program will lighten when switching 

Declaration of conformity:

 

Zewa Inc

 declares that the 

21021

 

complies with following normative documents:

IEC 60601-1, IEC 60601-1-2, IEC 62304, IEC 62366, IEC 60601-1-11,

IEC 60601-2-10, ISO 10993-5, ISO 10993-10

21021

21021

Zewa 

I

nc

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