Figure 1.1 Generalized instrumentation system The sensor
converts energy or information from the measurand to another form
(usually electric). This signal is the processed and displayed so
that humans can perceive the information. Elements and connections
shown by dashed lines are optional for some applications.
Slide 6
Measurand AccessibilityInternal On body surface Emanate from
the body Derived from a tissue sample CategoriesBiopotential
Pressure Flow Dimension Imaging Displacement (velocity,
acceleration, force) Impedance Temperature Chemical
concentration
Slide 7
1.3 Alternative Operational Modes
Slide 8
1.4 Medical Measurement Constraints
Slide 9
Ballistic = Gastric = Antimony = Sb,
Slide 10
galvanic skin response definition Function: n : a change in the
electrical resistance of the skin that is a physiochemical response
to emotional arousal which increases sympathetic nervous system
activity abbreviation GSRnervous systemabbreviation
Merriam-Webster's Medical Dictionary, 2007 Merriam-Webster, Inc.
Source: Dictionary.com, "galvanic skin response," in
Merriam-Webster's Medical Dictionary. Source location: Merriam-
Webster, Inc. http://dictionary.reference.com/browse/galvanic skin
response. Available: http://dictionary.reference.com. Accessed:
February 23, 2011.http://dictionary.reference.com/browse/galvanic
skin response http://dictionary.reference.com
Slide 11
pneumo- or pneum- pref. 1. Air; gas: pneumothorax . 2. Lung;
pulmonary: pneumoconiosis . 3. Respiration: pneumography a. . b. .
c. X . Pneumotachography . 4. Pneumonia: pneumococcus ,
Slide 12
To cope variability use assume empirical statistical and
probabilistic distribution functions Variability of measured
quantities: with time, among patients, anatomocal, interactions
among physiological systems, feedback loops, internal variability
(at molecular and organ levels),
Slide 13
1.5 Classification of Biomedical Instruments According to
what?Examples Quality that is sensedPressure, flow, temperature
TransductionResistive, inductive, capacitive, ultrasonic,
electrochemical Organ systemCardiovascular, pulmonary, nervous,
endocrine Clinical medicine specialtiesPediatrics, obstetrics,
cardiology, radiology Different classifications:
Slide 14
1.6 Interfering and Modifying Inputs
Slide 15
Slide 16
1.7 Compensation Techniques
Slide 17
Slide 18
1.8 Biostatistics
Slide 19
Slide 20
1.9 Generalized Static Characteristics
Slide 21
Slide 22
1.10 Generalized Dynamic Characteristics
Slide 23
Slide 24
1.11 Design Criteria
Slide 25
Figure 1.8 Design process for medical instruments Choice and
design of instruments are affected by signal factors, and also by
environmental, medical, and economic factors. (Revised from
Transducers for Biomedical Measurements: Application and Design, by
R. S. C. Cobbold. Copyright 1974, John Wiley and Sons, Inc. Used by
permission of John Wiley and Sons, Inc.) BMD = (Bone Mineral
Density) ?
Slide 26
Slide 27
1.12 Commercial Medical Instrumentation Development
Process
Slide 28
Slide 29
1.13 Regulation of Medical Devices
Slide 30
Classification of Medical Devices (Taiwan) 13 2
Slide 31
Categories of Medical Devices (Taiwan) 3 (Clinical chemistry
and toxicology devices) (Hematology and pathology devices)
(immunology and microbiology devices) (Anesthesiology devices)
(Cardiovascular devices) (Dental devices) (Ear, nose, and throat
devices) (Gastroenterology-Urology devices) (General and plastic
surgery) (General hospital and personal use devices) (Neurological
devices) (Obstetrical and gynecological devices) (Ophthalmic
devices) (Orthopedic devices) (Physical medicine devices)
(Radiology devices) (Other categories specified by the Central
Competent Health Authority)
Slide 32
FDA Classification (USA) FD&C Act 513 Class I 27% FDA FDA
GMP FDA Class II Class III Class II (Special Controls) FDA 60% FDA
(mandatory performance standards) Class III Class III 8% FDA PMA
Source:
Slide 33
1930sFederal Food, Drug, and Cosmetics Act May 28, 1976Medical
Device AmendmentsClasses I, II, III 7 Categories 1990Safe Medical
Devices ActFurther amendments
Slide 34
Medical Device definition by FDA [Source: Wikipedia] Definition
in USA by the Food and Drug Administration Medical Device
Definition A device is: "an instrument, apparatus, implement,
machine, contrivance, implant, in vitro reagent, or other similar
or related article, including a component part, or accessory which
is: - recognized in the official National Formulary, or the United
States Pharmacopoeia, or any supplement to them, -intended for use
in the diagnosis of disease or other conditions, or in the cure,
mitigation, treatment, or prevention of disease, in man or other
animals, or - intended to affect the structure or any function of
the body of man or other animals, and which does not achieve any of
it's primary intended purposes through chemical action within or on
the body of man or other animals and which is not dependent upon
being metabolized for the achievement of any of its primary
intended purposes.
Slide 35
Medical Device (defined by FDA) [Source FDA website] Medical
Device Definition Medical devices range from simple tongue
depressors and bedpans to complex programmable pacemakers with
micro-chip technology and laser surgical devices. In addition,
medical devices include in vitro diagnostic products, such as
general purpose lab equipment, reagents, and test kits, which may
include monoclonal antibody technology. Certain electronic
radiation emitting products 3 with medical application and claims
meet the definition of medical device. Examples include diagnostic
ultrasound products, x-ray machines and medical lasers. If a
product is labeled, promoted or used in a manner that meets the
following definition in section 201(h) of the Federal Food Drug
& Cosmetic (FD&C) Act it will be regulated by the Food and
Drug Administration (FDA) 4 as a medical device and is subject to
premarketing and postmarketing regulatory controls.radiation
emitting productsFood and Drug Administration (FDA)
Slide 36
Medical Device (defined by FDA) [Source FDA website] Medical
Device Definition A device is: "an instrument, apparatus,
implement, machine, contrivance, implant, in vitro reagent, or
other similar or related article, including a component part, or
accessory which is: recognized in the official National Formulary,
or the United States Pharmacopoeia, or any supplement to them,
intended for use in the diagnosis of disease or other conditions,
or in the cure, mitigation, treatment, or prevention of disease, in
man or other animals, or intended to affect the structure or any
function of the body of man or other animals, and which does not
achieve any of it's primary intended purposes through chemical
action within or on the body of man or other animals and which is
not dependent upon being metabolized for the achievement of any of
its primary intended purposes." This definition provides a clear
distinction between a medical device and other FDA regulated
products such as drugs. If the primary intended use of the product
is achieved through chemical action or by being metabolized by the
body, the product is usually a drug. Human drugs are regulated by
FDAs Center for Drug Evaluation and Research 5 (CDER). Biological
products which include blood and blood products, and blood banking
equipment are regulated by FDAs Center for Biologics Evaluation and
Research 6 (CBER). FDAs Center for Veterinary Medicine 7 (CVM)
regulates products used with animals. If your product is not a
medical device but regulated by another Center in the FDA, each
component of the FDA has an office to assist with questions about
the products they regulate. In cases where it is not clear whether
a product is a medical device there are procedures in place to use
DSMICA Staff Directory 8 to assist you in making a
determination.Center for Drug Evaluation and ResearchCenter for
Biologics Evaluation and ResearchCenter for Veterinary
MedicineDSMICA Staff Directory
Slide 37
FDA Classification [Source: Wikipedia] United States The Food
and Drug Administration has recognized three classes of medical
devices based on the level of control necessary to assure the
safety and effectiveness of the device. [7] The classification
procedures are described in the Code of Federal Regulations, Title
21, part 860 (usually known as 21 CFR 860). [8] [7]Code of Federal
Regulations [8] Class I: General controls Class I devices are
subject to the least regulatory control. Class I devices are
subject to General Controls as are Class II and Class III devices.
General controls include provisions that relate to adulteration;
misbranding; device registration and listing; premarket
notification; banned devices; notification, including repair,
replacement, or refund; records and reports; restricted devices;
and good manufacturing practices. Class I devices are not intended
for use in supporting or sustaining life or to be of substantial
importance in preventing impairment to human health, and they may
not present a potential unreasonable risk of illness or injury.
Most Class I devices are exempt from the premarket notification
and/or good manufacturing practices regulation. Examples of Class I
devices include elastic bandages, examination gloves, and hand-held
surgical instruments.
Slide 38
FDA Classification (cont.) [Source: Wikipedia] Class II:
General controls with special controls Class II devices are those
for which general controls alone are insufficient to assure safety
and effectiveness, and existing methods are available to provide
such assurances. In addition to complying with general controls,
Class II devices are also subject to special controls. [9] A few
Class II devices are exempt from the premarket notification. [9]
Special controls may include special labeling requirements,
mandatory performance standards and postmarket surveillance. [9]
[9] Devices in Class II are held to a higher level of assurance
than Class I devices, and are designed to perform as indicated
without causing injury or harm to patient or user. Examples of
Class II devices include powered wheelchairs, infusion pumps, and
surgical drapes. [7][9] [7][9] Class III: general controls and
premarket approval A Class III device is one for which insufficient
information exists to assure safety and effectiveness solely
through the general or special controls sufficient for Class I or
Class II devices. [7][9] [7][9] Such a device needs premarket
approval, a scientific review to ensure the device's safety and
effectiveness, in addition to the general controls of Class I.
[7][9] [7][9] Class III devices are usually those that support or
sustain human life, are of substantial importance in preventing
impairment of human health, or which present a potential,
unreasonable risk of illness or injury. [9] [9] Examples of Class
III devices which currently require a premarket notification
include implantable pacemaker, pulse generators, HIV diagnostic
tests, automated external defibrillators, and endosseous (placed or
contained within a bone) implants. [9] [9]
Slide 39
FDA Medical Device Categories
Slide 40
FDA Medical Device Categories (cont.)
Slide 41
Category: Preamendment devices
Slide 42
Category: Postamendment devices Fetoprotein ; radioimmunoassay
(RIA) Radioimmunoassay (RIA), an in vitro nuclear medicine, is a
very sensitive technique used to measure concentrations of antigens
(for example, hormone levels in the blood) by use of antibodies.
(Source: Wikipedia)in vitronuclear medicine antigenshormoneblood
Extracorporeal shock wave lithotripsy (ESWL) is the non-invasive
treatment of kidney stones (urinary calculosis) and biliary calculi
(stones in the gallbladder or in the liver) using an acoustic
pulse. (Source: Wikipedia)non-invasivekidney stones biliary
calculigallbladderliver
Category: Transitional devices Transitional ; Gonorrhea ;
heterograft An intraocular lens (IOL) is an implanted lens in the
eye, usually replacing the existing crystalline lens because it has
been clouded over by a cataract, or as a form of refractive surgery
to change the eyes optical power. [Source:
Wikipedia]lenseyecrystalline lenscataractrefractive surgeryoptical
power
Slide 48
From 3 rd Edition
Slide 49
Figure 1.2 Simplified electrocardiographic recording system Two
possible interfering inputs are stray magnetic fields and
capacitively coupled noise. Orientation of patient cables and
changes in electrode-skin impedance are two possible modifying
inputs. Z 1 and Z 2 represent the electrode-skin interface
impedances. Electrodes 60-Hz ac magnetic field Displacement
currents Differential amplifier + +V cc - V cc Z1Z1 Z body Z2Z2
vovo v ecg
Slide 50
(x d H f y)G d = y(1.1) x d G d = y(1 + H f G d )(1.2) (1.3)
(1.4) (1.8) (1.7) (1.6) (1.5)
Slide 51
Figure 1.3 (a) Static-sensitivity curve that relates desired
input x d to output y. Static sensitivity may be constant for only
a limited range of inputs. (b) Static sensitivity: zero drift and
sensitivity drift. Dotted lines indicate that zero drift and
sensitivity drift can be negative. [Part (b) modified from
Measurement Systems: Application and Design, by E. O. Doebelin.
Copyright 1990 by McGraw-Hill, Inc. Used with permission of
McGraw-Hill Book Co.] Intercept b xdxd y x' d y' y (Output) y = mx
d + b x d (Input) (a) Slope m = yy xdxd Total error due to drift
Characteristic with zero and sensitivity drift + Zero drift +
Sensitivity drift Sensitivity drift Zero drift (b) y (Output) x d
(Input)
Slide 52
(1.11) (1.9) (1.10)
Slide 53
Figure 1.4 (a) Basic definition of linearity for a system or
element. The same linear system or element is shown four times for
different inputs. (b) A graphical illustration of independent
nonlinearity equals A% of the reading, or B% of full scale,
whichever is greater (that is, whichever permits the larger error).
[Part (b) modified from Measurement Systems: Application and
Design, by E. O. Doebelin. Copyright 1990 by McGraw-Hill, Inc. Used
with permission of McGraw-Hill Book Co.] x d (Input) B% of full
scale A% of reading Overall tolerance band Least-squares straight
line (a) (b) Point at which A% of reading = B% of full scale y
(Output) x1x1 (x 1 + y 2 ) y1y1 x2x2 Kx 1 Ky 1 y2y2 Linear system
Linear system Linear system Linear system and (y 1 + y 2 )
Slide 54
(1.12) (1.13) (1.14) (1.15) (1.16) (1.17)
Slide 55
Figure 1.5 (a) A linear potentiometer, an example of a
zero-order system. (b) Linear static characteristic for this
system. (c) Step response is proportional to input. (d) Sinusoidal
frequency response is constant with zero phase shift.
Slide 56
(1.18) (1.19)
Slide 57
Figure 1.6 (a) A low-pass RC filter, an example of a first-
order instrument. (b) Static sensitivity for constant inputs. (c)
Step response for larger time constants ( L ) and small time
constants ( S ). (d) Sinusoidal frequency response for large and
small time constants. t 1 (c) (a) C + + y(t)y(t) Output y(t) Input
x(t) Slope =K = 1 (b) Y (j X (j Log scale 1.0 0.707 Log scale (d) 0
45 90 Log scale t 1 0.63 LL SS LL SS SS LL LL SS y(t)y(t) x(t)x(t)
x(t)x(t) y(t)y(t) R
Slide 58
(1.20) (1.21) (1.22) (1.23) (1.24)
Slide 59
Figure 1.7 (a) Force-measuring spring scale, an example of a
second-order instrument. (b) Static sensitivity. (c) Step response
for overdamped case = 2, critically damped case = 1, underdamped
case = 0.5. (d) Sinusoidal steady-state frequency response, = 2, =
1, = 0.5. [Part (a) modified from Measurement Systems: Application
and Design, by E. O. Doebelin. Copyright 1990 by McGraw-Hill, Inc.
Used with permission of McGraw-Hill Book Co.] Output displacement
Outputy(t) (b)(a) (d)(c) 1 KsKs x(t)x(t) y(t)y(t) ynyn y n + 1
Resonance 2 Log scale 1 2 -90 0.5 1 2 -180 1 0.5 Log scale K 1 t t
Input x(t) Slope K = 1 KsKs Input Force x(t) 0 00 nn nn Y (j X (j
y(t)y(t)