BMME 111BME422

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BMME 111/BME422
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Objectives of this course

• a.      Introduction to types of biophysical
  instruments and transducers used in hospitals and
  research laboratories.
• b.      Review basic electronic circuit theory so
  that students can build basic biomedical
  instruments in the laboratory and so that they
  can understand the internal design in medical
  instrumentation.

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Objectives of this course

• a.      Survey basic principals in biophysical
  transducers to understand what they can do and
  their limitations
• b.      Visit clinics in the hospital to see
  these instruments in use and meet the doctors,
  nurses and patients that use them
• Guest lectures by physicians to understand the
  clinical constraints on instrument design

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Structure of Course

• a.       Lectures twice a week - Tuesday
  Thursday 220-325 pm
• b.       Laboratories -4 hr/week, optional
• c.       Homework 1 problem set/week
  (late papers penalized)
• d.       Hospital visits tba
• e.       Final Project with report
• f.         Exams Midterm and Final
• g. 4 credit hours

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Textbook

• Webster Medical Instrumentation- Application and
  Design John Wiley
• (recommended but not required)

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Voltage Definition

• Definition of potential
• Relative to reference
• Polarity

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AC-DC-RMS
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Ground Definitions

• Common
• Ground (Neutral)
• Earth
• Plug wiring
• House wiring

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Current Definitions

• Charge
• Direction
• Component definition

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Measurement Principles

• Accuracy NBS reference
• Precisian repeatability
• Sensitivity (type 1) loading effect of
  instrument
• Sensitivity (type 2) delta output/delta input
•  

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Basic electrical safety concepts

• Current, not voltage, is dangerous
• Current (100ma -2 amp) passing through heart can
  cause ventricular fibrillation
• Higher currents (10A) cause severe burns
• Cant let go current levels are dangerous
• Minimum current exposure from devices is 500uamp,
  and new heart is 15 uamps

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Safety notes

• Most dangerous current frequencies are in 50-60Hz
  region
• High voltage lease pin prick holes in skin
• 3rd wire on plugs are safety wire which carry
  current to earth. This is connected to outside
  metal of devices
• Safety current trip sensors (ground fault
  devices) detect 25 ma on this wire.

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Safety notes

• Hospital plugs are designed to have a minimum
  force to be pulled out
• Plugs are transparent so that the connection to
  the wires can be visually examined
• Typical resistance in skin is about 20K ohms.
  You can calculate the hazard at low voltages
  (15V) and high voltages (110vac)
• Most other countries use 220vac, Japan 100vac
• Special plugs for foreign countries