Transcutaneous Electrical Nerve Stimulation TENS

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Transcutaneous Electrical Nerve Stimulation (TENS)
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Main Points

• Mechanism of pain.
• Functions and features of TENS unit .
• Circuit Design.
• Realizing Design into Hardware.
• Results.
• Conclusions .

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Mechanism of Pain

• Pain is felt as a result of the brain's response
  to electrical (neural) and chemical (hormonal)
  changes in the body as a result of damage.
• Signals from damage or injury are picked up by
  sensory receptors in nerve endings. The nerves
  then transmit the signal via the nerves to spinal
  cord and brain.

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Mechanism of Pain
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Pain Relief

• Pain can be managed in the short term using
  analgesics, but long-term use can be detrimental
  to the patient's health.
• Side effects of the long use of analgesics may
  affect on liver, kidney or stomach.
• In many cases where pain is constant, a medical
  practitioner or physiotherapist may recommend the
  use of a TENS unit.
• Why TENS?
• Because it is safe, effective and virtually
  with no side effects.

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Functions and Features of TENS

• A TENS unit provides electrical stimulation to
  the painful area using electrodes attached to the
  skin.
• Some scientists say
• electrical signal
• v
• nerve sensation stops
• v
• natural pain relieving substances
  (endorphins)
• v
• no pain massages to brain
• v
• no pain.

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Features

• 1- Two different modes
• a- Continuous (continuous stream)
• b- Intermittent (short bursts)
• Usually the continuous mode is used but for long
  term treatment intermittent mode is used
• 2- Adjustable.
• We can control three variables
• a- Output voltage.
• b- Width of the pulses.
• c- Pulse rate.

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Features

• Continuous Mode
• Output Voltage Adjustable from 12V to 80V.
• Pulse Rate Adjustable from 4.6Hz to 410Hz.
• Pulse Width Adjustable between 70 and 320
  µs.
• Intermittent Mode
• Duty cycle 24 at 1.2Hz

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Circuit Design of the Device

• 9 volts battery
• Step up converter composed of transformer and DC
  to DC converter.
• Switching oscillator.
• Intermittent oscillator.

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Circuit Diagram
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Realizing Design into Hardware

• Collecting components flight
• We call it flight because we had to bring the
  components from overseas. Unfortunately the
  components were collected from Riyadh, Jeddah,
  Jordan, Japan and China.

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Making Project Board

• We connected the components in our project board
  as shown in figure to test the function of the
  circuit.
• After that we tested the circuit connections and
  circuit output we corrected the faults that
  raised.

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Make PCB

• We used OrCAD program to make the layout.

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• After that we printed the layout in PCB by using
  ultraviolet exposure unit ,then we started
  mounting components on the PCB.

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Results

• Continuous mode
• The output volt79v.
• The frequency362 Hz.

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Results

• Intermittent mode
• The output volt82v
• The frequency108 Hz.

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Discussion

• Due to the small size and light weight of the
  TENS device, we think we can integrate it with
  other medical devices like therapeutic ultrasound
  which is used sometimes to reduce joints
  stiffness.

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Discussion

• In this device there are only two electrodes, so
  we think it will be a good idea to double the
  electrodes to cover more muscles.

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Discussion

• Placing the electrodes was a little problem for
  us because the adhesive substance is not
  effective for long time ,so we had an idea to
  implant the electrodes inside sock to be worn
  during the therapy , also make a gloves for
  hand's muscles.

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Discussion

• This device might be used to treat the face
  muscles. (Bell's Palsy disease) , This is often
  due to the partial facial paralysis that occurs
  on one side of the face.In this case the face
  muscle is small compared to other muscles ,so we
  need small electrodes to capture the effected
  muscles .

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Conclusions

• We could reach our goals to make a medical device
  that relief chronic and acute pains started with
  studying the electrophysiological parameters,
  then studying design stages of the circuit which
  gives these parameters as output. After that we
  applied the studies from paper to the practical
  work.
• During all stages of the project we had to solve
  some problems which we got by applying the
  designed circuit onto circuit board, we corrected
  it to get the expected results. Finally, we
  tested the output of the circuit by applying the
  output directly to the muscle.

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