Endoscope Lens Defogger

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Endoscope Lens Defogger

• Group Members
• Eric Wilkinson
• Richard Dixon
• Brett Vandenhouten
• Daniel Chicola

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Micro Series Thermistor

• Accurate
• Built for Small Space
• Fast Response

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Applications of Thermistors
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Bridge Circuit

• Ra, Rb, and Rc are all constant
• Rs is the sensitive resistor
• As the temperature increases, the resistance of
  Rs decreases.

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History of the Thermistor

• Michael Faraday - 1833
• Named by Bell Telephone Laboratories
• Been in use for last 30 years in telephones
• In the last 20 years, semiconductor design has
  led to advances in production.

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Thermistor

• Resistive Sensor
• Sensor is made of a semiconductor strip
• Voltage divider concept

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Resistance vs. Temperature

• Assumed as linear
• Resistors use lowest value of k possible
• Sign of k determines the type of thermistor,
  either PTC or NTC.

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How does it work?

• The Steinhart-Hart equation shows how the
  resistance of the device determines the
  temperature
• a, b, and c are whats known as the Steinhart
  parameters and differ from device to device
• T is the temperature in Kelvin and R is the
  resistance in ohms

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Parameters for Micro Sensor

• a .001294
• b 2.726e-4
• c 8.075e-8
• The ground resistance of the sensor at room
  temperature (25 degrees C) is 2,252 ohms.

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Thermistor has a resistance of 2,252 ohms at room
temperature.
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Thermistors Size and Accuracy

• Thermistor used in our project is 56A2251-C8.
• Thermistor has temperature tolerance of 0.2C in
  the temperature range of 0C to 50C.
• Available with outer diameters of 0.0185 in.
  high, 0.035 in. wide, and 0.065 in. long.

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Properties of Thermistor

• Thermistor CoatingEpoxy filled PVC Cup 0.078
  Max. O.D.
• Lead Materials400 Series AWG 28 Twisted Kynar
  Insulated Silver PlatedCopper Conductors

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Thermal Regulating Scope Sleeve

• The heated scope will overcome the temperature
  gradient and eliminate fogging
• Thermistors will be mounted in the sleeve as well
  as a Heating Coil

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CAD Representation
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Project Need

• Shorten surgery length
• Reduce repeated removal and insertion of scope
• Increase efficiency in operating room

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Similar Products Available
Premium Seals
Scope Warmer
Disposable Plastic Cannula
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Manufacturing Costs and Benefits

• Minimal Material Costs
• Garrett Electronics Corporation
• Maximum Medical product development/ marketing
  costs
• Extremely high potential for earnings

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Medical Benefits

• All patients who undergo surgery
• Efficiency in the Operating Room
• Increased surgical precision

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• Thank you for this opportunity to share our
  design and innovation
• At this time are there any questions?