Nu talk

Optical fiber sensors for biomedical applications !

[Nazarbayev University Seminar - Feb 2015]

Daniele Tosi !

Nazarbayev University School of Engineering, EEE Department

[email protected] !

mailto:[email protected]

mailto:[email protected]

Daniele Tosi - Optical Fiber Sensors for Biomedical Application - NU 2015

Overview


‣ Optical fibers and sensors

‣ Technology highlights

‣ Our biomedical sensors

‣ Projects, applications, and results

‣ Future development

Amongst all known mediums to

transport waves, optical fibers have

the smallest attenuation

Optical fibers


cladding core

Optical fiber: cylindrical guiding structure for light Light travels by means of total internal refraction (TIR) on the borders

Standard fibers are made on silica (glass): $0.08/m

80-250μm

Telecom (devices) Sensors

Overview







OFS identity


Size: down to 80μm

EMI/MRI-immune

Chemically inert

Top performance

Principles


Target-based

Macro-bending

Principles


Fiber Bragg grating (FBG) Fabry-Perot interferometry (FPI)

Surface plasmon resonance (SPR)

Interferometry Hollow-core fibers Photonic crystal fibers Evanescent-field …

Distribution


Punctual

Distributed

Arrayed

Integrated

1544 1546 1548 1550 1552 15540

1

2

3

4

5 x 104

Wavelength (nm)

Inte

nsity

(a.u

.)

0s45s84s

!

Overview







Goal


‣ Pressure sensor with <1 mmHg accuracy

!

‣ Integrate with temperature sensor

!

‣ Expand temperature distribution

Air-gap length L FP Spectrum ~

d L

Pressure

Air-gap length FP Spectrum ~ Temperature:

L0 - Sp ΔP

L

fs laser inscription


Femtosecond laser pattern

fs laser inscription


Inscription performed at Cyprus Institute of Technology


Biocompatible

Spectra


Temperature

Pressure

Calibration


Competitor’s sensor


Our sensor


System


Comparison


Our sensors Opsens St Jude

Technology Fiber optic Fiber optic Guidewire

Diameter 0.2 mm 0.2-0.5 mm 0.35 mm

Accuracy 0.05 mmHg 1 mmHg 2 mmHg

Speed 100 Hz 20-250 Hz 25 Hz

Stability 0.2 mmHg/hr 0.2 mmHg/hr >5 mmHg/hr

Temperature Compens. 1.6 mmHg/˚C 3 mmHg/˚C

Biocompatible Yes Not really Yes

Overview







Application areas


‣ Thermal ablation of tumors

‣ Urodynamics

‣ Fractional flow reserve

Thermal ablation: generate a “sphere”

of heat that kills tumor cells

RFTA


10 mm

Monitoring available only on surface, or ex

vivo. Sensors can perform monitoring at the point of treatment

in vivo!

Percutaneous (outpatient)

Smart-RFTA


10 mm

RF source

Ablator

Tissue Imaging

RF ablation

Sensors

Smart

Power Frequency

Shape/position

Setup


Temperature

Pressure

Pressure


0 0.2 0.4 0.6 0.8 1−15

10

35

60

85

110

135

160

Pres

sure

(kPa

)

0 0.2 0.4 0.6 0.8 120

45

70

95

120

145

170

Tem

pera

ture

(o C)

Exp.1 (1mm)Exp.2 (5mm)Exp.3 (8mm)

Normalized time

The only prior experiment was performed at 3 cm distance from ablation point!

Temperature


8 radii with Luna OBR4600

Fusion: spatial distribution

Comparison


0 0.2 0.4 0.6 0.8 1 1.20

20

40

60

80

100

120

140

Normalized time

Tem

pera

ture

(°C

)

DTS, 0mmDTS, 20mmFBG, 0mmFBG, 20mmLCFBG, 0mmLCFBG, 10mm

Abdominal P Bladder P

Bladder

Urethra

Prostate

Pre

Post

Bladder outlet obstruction

Urodynamic analysis


Optical fiber

Reference

Differential

Fill/void V

Pressure differential


FM

MFPressure differential vs

pressure level, recorded in vivo for first time in M and F patients with suspected bladder conditions.

Correlation with volume of solution infused

Improving FFR


Current FFR: the clinician acquires 2 non-simultaneous pressure values moving guide wire

Improved FFR: the clinician acquires 2+ simultaneous pressure values, without moving cable (long term)

LVAD measurement


FPI positioning

Ventricular assist

Reference (fluidic)Pressure readout

March 2013, Cleveland

Heart simulator


Heart simulator

Interrogator/processing

Heart pumpingEFPI spectrum

Pressure meas.

Spectrometer ASE source

Heart pumpinginletFiber inlet

Sensor positioning (short access)

Femoral artery


Mid-term (8hrs) monitoring of femoral artery: 2x pressure

Overview







TA Tour 2015


Politecnico di Torino Integration of laser ablator and sensors on same fiber

Biomedical Campus Rome Pressure measurem. in laser

ablation of pancreas tumours

Universita’ di Pavia Multi-pressure measurement

3D temperature measur.

Ongoing


Come up with the best positioning of a multi-sensors probe that has max chances to record an obstruction

Development of first-ever working algorithm for distributed detection

of a chirped grating

Integrate a high-power fiber laser with fiber-optic sensors on same fiber

Polarization beam steering

Help wanted!

Acknowledgments


Funding agencies:

‣ FP7 - Marie Curie Actions

‣ Enterprise Ireland

‣ Science Foundation Ireland

‣ FP7 - COST network

‣ CMT Foundation

Acknowledgments


Partners:

‣ University of Limerick (Ireland) ‣ Federico II University (Italy) ‣ Universita’ di Pavia (Italy) ‣ Politecnico di Milano (Italy) ‣ Politecnico di Torino (Italy) ‣ Cyprus Institute of Technology (Cyprus) ‣ FBGS International (Belgium) ‣ Endophys (US) ‣ Cleveland Clinic (US)

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