Ultrasonic Array of Thick Film Transducers for Biological Tissue Characterization
Sergio N. Gwirc
Néstor R. Mariño
sng@inti.gob.ar
nmarino@inti.gob.ar
Instituto Nacional de Tecnología Industrial – Electrónica e Informática,
San Martín, Buenos Aires, Argentina.
Carlos A. Negreira
carlosn@fisica.edu.uy Instituto de Física, Laboratorio de Acústica Ultrasonora, Facultad de Ciencias,
Montevideo, Uruguay.
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina
Thick Film Transducer
PZT
ALUMINA
Disc
ELECTR ODS
Outline of the Basic Thick Film Transducer
Actual Thick Film Transducer Diameter: 4 mm
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina
2
Manufacturing Process
y Screen printing on substrate
y Drying
(120 ºC to remove solvent)
y Sintering (850 ºC)
y Paste
Solid
y Polarization: 2500 V/mm, 110 ºC
(Curie Temperature: ∼350 °C)
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina
3
Structure of the Paste and Sintered PZT
Material
PZT powder: PZ27 (Ferroperm)
Frited glass:
Substrate adhesion Glue PZT particles
ρ
K33
(kg/m3) (ε/εo)
d31 (C/N)
d33 (C/N)
k33
kt
PZ 27 7,7x103 1800 -170x10-12 425x10-12 0,70 0,47
PZT Microstructure
Porosity ρ (PG) 20% < ρ (solid)
Micrografía obtenida con MEB (2400x)
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina
4
Pulsed Response and Fourier Spectrum I
Normalized Amplitude
1 0.6
0.2 0 -0.2
-0.6
-1 0
0.5
1
1.5
2
2.5
3
3.5
Tiempo (µs)
0 -20 -40
-60
-80 -100
-120 02
4 6 8 10 12 14 16 18 20
Frecuencia (MHz)
Without Backing
Backing
PZT Al2O3
fr: 3,8 MHz BW(-6dB): 0,6 MHz
Amplitude (dB)
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina
5
Pulsed Response and Fourier Spectrum II
Amplitud normalizada
1 0.8
0.6 0.4 0.2
0
-0.2 -0.4
-0.6
1.6 1.8 2
2.2 2.4 2.6 2.8 3
3.2
Tiempo (µs)
0
-20
-40 -60 -80
-100 0
5
10
15
20
25
Frecuencia (MHz)
With Backing
Backing
PZT Al2O3
Glass
fr: 3,5 MHz BW(-6dB): 1,9 MHz
Amplitud (dB)
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina
6
Radiation Field (by schlieren)
Effects of two-layer building
Ratio of transmission coefficients:
RT
= TTF -H2O TAl3O2 -H2O
≅ 2.1
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina 7
Radiation Field (by schlieren)
Effects of two-layer building
Ratio of transmission coefficients:
RT
= TTF -H2O TAl3O2 -H2O
≅ 2.1
Normalized Intensity (%)
100 90 80 70 60 50 40 30 20 10
0 1.5
3.05 MHz
3.15 MHz
---- Bulk Ceramic ---- Thick Film
2
2.5
3
3.5
4
4.5
Frequency (MHz)
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina 8
Pulse Visualization
8 µs from emission
2 µs from emission
Transducer location
Array location
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina
Ultrasound B of a “phantom”
Phantom simulating human tissue with agar. Inclusions of 3 mm in diameter: different density. Density differences between tumors 30%.
Tumors
Dead Zone
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina 10
Thick Film Arrays
• Array: 16 x 15 elements. • Substrate: 50 x 50 mm. • Transducers Elements: 1,5 x 1,5 mm.
Mounting of a linear array for testing
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina 11
Conclusions
y Good coupling with human tissue y Easy to make different geometries y Two resonance frequencies y Manufacture arrays in a few steps y Wide bandwidth y Compatibility with hybrid electronics devices
IEEE EMBC 2010 - 31 August - 4 September, Buenos Aires, Argentina
Thank you very much
Ver+/-
