HiHsiao-LChPhDLung Chan, Ph.D. Dept Electrical … · S. Franco, “Design with Operational Amplifiers and HL Chan , EE, CGU Medical instrumentation 9 Analog Integrated Circuits”,

BioinstrumentationBioinstrumentation

H i L Ch Ph DHsiao-Lung Chan, Ph.D.Dept Electrical Engineering

Chang Gung University, [email protected]@ g

Operational amplifierOperational amplifier

P ti l Id lPractical Ideal

HL Chan , EE, CGUBioinstrumentation 2

Open- and close-loop gainOpen and close loop gain


Inverting amplifierInverting amplifier

V out / V in = - ( Rf / Rin )V out / V in ( Rf / Rin )


Inverting amplifier (cont )Inverting amplifier (cont.)


Noninverting amplifierNoninverting amplifier

V o / V i = 1 + ( Rf / RG )


Noninverting amplifier (cont )Noninverting amplifier (cont.)


Biopotential signalsBiopotential signals

110

210

310

(V)

510

410

10

1 0 1 2 3 4110 010 110 210 310 410(Hz)


Analog gfilters

S. Franco, Design with Operational Amplifiers and

HL Chan , EE, CGUMedical instrumentation 9

Analog Integrated Circuits, Second Edition, 1998.

Frequency compositionFrequency composition


Passive filtersPassive filters


Active filterActive filter


First-order lowpass active filterFirst order lowpass active filter

)/(11)(

0ffjHjfH DC

sCR

RRVVsH F

in

O

1

/1)( 1)( 0ffjin

10 12

1RRHand

RCfwhere FDC


Bode plotBode plot


First-order highpass active filterFirst order highpass active filter

sCRsCR

RR

VVsH F

i

O

1)1()(

1 )/(1)/()(0

0

ffjffjHjfH DC

10 12

1RRHand

RCfwhere FDC

sCRRVin 11 )/(1 0ffj


Bandpass filterBandpass filter

1R

C

2C

R 1C fR

gR

2R fR

gR

(H )

(V)

(Hz)


1st- vs 2nd-order filters1st vs. 2nd order filters

iE iEi i

-20 dB/decade -40 dB/decade

(V)

(V)

cof cof(Hz) (Hz) (a) (b)


Second-order filtersSecond order filters

Low-pass response High-pass response

S. Franco, Design with Operational Amplifiers and Analog Integrated Circuits, Second Edition, 1998.


Second-order Sallen-Key lowpass filterSecond order Sallen Key lowpass filter

200 )/()/)(/(1

1)(ffffQj

HjfH DC

)1(121 ,1 0

DCA

BDC Hmnm

mnQandmnRC

fRRHwhere


Second-order Sallen-Key highpass filterSecond order Sallen Key highpass filter

200

20

)/()/)(/(1)/()(

ffffQjffHjfH DC

)1(121 ,1 0

DCA

BDC Hmnn

mnQandmnRC

fRRHwhere

)1(12 DCA HmnnmnRCR


Differential amplifierDifferential amplifier

RRR1

12

32

3

1

)1( VRRV

RRR

RRV FFo

RRRRid = R1 +R2

2

3

112

1

)(RR

RRifVV

RR FF


Instrumental amplifier (IA)Instrumental amplifier (IA)

1E

1A3R 5R1 CMV V

1 fR R

3A outVGR

2A2 fR R

E

4R

V V 2E2 CMV V

6R

))(2

1( 215 VVRR

RRV fo

3 RR GHL Chan , EE, CGU

Bioinstrumentation 22

INA118 IAINA118 IA

V

7

V

G

50 kA 1R

1A

25 k60 k 60 k

1

2

25 k

3A25 k

60 k 60 k8

6GR

2A

60 k 60 k

3

5

4

out fV

V 2R1 A

4

V

V1 2 G

1 AV V R

HL Chan , EE, CGU


Cancellation of common-mode voltage by IACancellation of common mode voltage by IA


Differential- and common-mode inputsDifferential and common mode inputs

V = A V + A VVo = A d V d + A cm V cm

Ideally, A cm = 0

Common-mode rejection ratio

CMRR = 20 log10 | A d / A cm | =


ECG amplifierECG amplifier


Power interference in ECG measurementPower interference in ECG measurement

Power line, 120V, 50/60 Hz

C CC3

iCb ib

- Zs1

C2 C1

id1

id3 b

Shielding

InstrumentalAmplifierRgZs2

id2

Driven-right

p

+

Zcm

Driven rightleg circuit


Common-mode voltage in ECG measurementCommon mode voltage in ECG measurement

id

Induced Current from power-line

Differential voltage generated from heart

Z 1 _ +Vd -

InstrumentalR

Zs1

InstrumentalAmplifier

+

Rg Zs2

Zcm

Common-mode voltage caused by id

Vcm _ +

Driven-rightleg circuit


Electrode-tissue interfaceElectrode tissue interface

hcV

hc

dC dR

gR

hc

d d

VC , RR

g

gsV

eC eR

g

gs

e e

R

V

C , R

tR

e e

t

C ,R


Impedance mismatch in ECG measurementImpedance mismatch in ECG measurement

Degradation of CMRR due to nonzero source resistance and parasitic capacitance

-V1 C1

Rs1

I A

+

Vo

+Vcm

Rg

C2 Rs2 + -Vcm V2

V1V2 due to Rs1C1 Rs2C2


Driven-right-leg circuitDriven right leg circuit

+

Rs1Vcm

- Rs2

R'Vcm

cm

RcmRa

Rg

Ra R'

Vcm

+

- Rf

+

-+


Driven-right-leg circuit (cont )Driven right leg circuit (cont.)

02/

ocmRV

RV Ra/2

2/ fa RR + -Vcm

cmf

o VRR

V2

Vcm id Rf

f RiVVR2

aR

+

-

Vo

Rcmcmdcmcm

a

f RiVVR

cmd RiVaf

cmdcm RR

V/21


Driven-right-leg circuit (cont )Driven right leg circuit (cont.)

i = 0 2 A A worst case electrode resistance R = 100 k id = 0.2 A. A worst-case electrode resistance Rcm = 100 k, R a and R f are selected as 25 k and 5 M respectively. Find Vcm.

VkMAkVcm

5025/521

2.0100

cm

kM 25/521

If no right-leg-driven circuit

mVAkRiV cmdcm 202.0100


ECG amplifierECG amplifier


Second-order band-reject filtersSecond order band reject filters

S. Franco, Design with Operational Amplifiers and Analog Integrated Circuits, Second Edition, 1998.


Twin-T notch filterTwin T notch filter

+

- Vo R R

Vi

2C

- +

R2 R/2

CC R1

CC

)/(1)(2

0ffjfH )/)(/()/(1

)(0

20 ffQjff

jfH

1

01,

21

RQand

RCfwhere

21

114RR

RC


Twin-T notch filter (Cont )Twin T notch filter (Cont.)

From WJ. Tompkins, JG. Webster. Design of Microcomputer-Based Medical Instrumentation, Prentice-Hall, 1981.


Electrocardiogram (ECG)Electrocardiogram (ECG)

22III

IRVVLLLARAaV

22I

IIIIIL

VVRALALLaV

VVLLRALAaV

22 IIFVLLaV

IIIIII VVV HL Chan , EE, CGUBioinstrumentation 38

ECG using augmented leadsECG using augmented leads

From JJ Carr, Introduction to Biomedical Equipment Technology, Prentice-Hall, 1998.


ECG using chest leadsECG using chest leads

From JJ Carr, Introduction to Biomedical Equipment Technology, Prentice-Hall, 1998.


ECG Using chest LeadsECG Using chest Leads


12-Lead ECG Precordial leads: V1-V612 Lead ECG

Ei th l d I II & IIIEinthoven leads: I, II & III

Goldberger augmented leads: VR VL & VFGoldberger augmented leads: VR, VL & VF


Isolation amplifierIsolation amplifier

Basic architecture

Equivalent 108 1012 108 ~ 1012

InputAmplifier Modulator Demodulator

OutputAmplifier

Isolation barrier,can be magnetic transformer, optical, capacitive


Transformer-coupled isolation amplifierTransformer coupled isolation amplifier


Transformer-coupled isolation amplifier(ISO212, Burr-Brown Corporation)


Optical-coupled isolation amplifierOptical coupled isolation amplifier


Optical-coupled isolation amplifier(ISO100 Burr Brown Corporation)(ISO100, Burr-Brown Corporation)


Differential-Capacitive Isolation Amplifier(ISO121 Burr Brown Corporation)(ISO121, Burr-Brown Corporation)

HL Chan , EE, CGUMedical instrumentation 48

Electromyography (EMG) amplifierElectromyography (EMG) amplifier


Integrated EMG (IEMG)Integrated EMG (IEMG)

IntegratedEMG

OriginalEMG


Analog channel-to-channel isolationAnalog channel to channel isolation

From JJ Carr, Introduction to Biomedical Equipment Technology, Prentice-Hall, 1998.HL Chan , EE, CGU


Analog isolationAnalog isolation



Digital isolationDigital isolation



Digitization trend in physiological monitoringDigitization trend in physiological monitoring


Multichannel EEG recodeings: NeuroscanTMMultichannel EEG recodeings: Neuroscan


Other applications based on IAOther applications based on IA

V

V

V

oVGR


pH measurementpH measurement

V

oVGR


Direct blood pressure measurementDirect blood pressure measurement


Strain-guage transducerStrain guage transducer

displacementdisplacement

stretchedAllAl )(

Allllll

Al

lAll

Al

AllR

stretched

)2()()( 2222

stretched

AlAlAAAstretched

Rl

lA

lR 22lA


Indirect blood pressure measurementIndirect blood pressure measurement


Indirect blood pressure measurementIndirect blood pressure measurement

mH

g)

(mm

IC


Measurement of pressure waveMeasurement of pressure wave

10 V 10V

7

2

11

outV8

32

1 6

5

INA 118

32

6

4

MRL -5GINA 118

5


Blood pressure waveformBlood pressure waveform


Indirect blood pressure measurement with automatic pumping


Continuous noninvasive blood pressure measurement (NIBP)

Arterial tonometer


Continuous NIBPContinuous NIBP

IEEE Engineering in Medicine and Biology Magazine, 2005


Continuous NIBP (cont )Continuous NIBP (cont.)

IEEE Engineering in Medicine and Biology Magazine 2005Magazine, 2005


ReferenceReference

2010 2010. 2008. JJ.Carr, JM.Brown, Introduction to Biomedical Equipment Technology, JJ.Carr, JM.Brown, Introduction to Biomedical Equipment Technology,

4nd Edition, Prentice-Hall, 2000. JG. Webster, Medical Instrumentation, application and design, 3rd,

Houghton Mifflin 2000Houghton Mifflin, 2000. JJ.Carr, JM.Brown, Introduction to Biomedical Equipment Technology,

4nd Edition, Prentice-Hall, 2000. S. Franco, Design with Operational Amplifiers and Analog Integrated

Circuits, Second Edition, 1998.

Documents

HiHsiao-LChPhDLung Chan, Ph.D. Dept Electrical … · S. Franco, “Design with Operational Amplifiers and HL Chan , EE, CGU Medical instrumentation 9 Analog Integrated Circuits”,