Infotech Oulu Annual Report 2014 - New Generation Optoelectronics for Measurement Applications (NEGOMA)

Emeritus Professor Risto Myllylä, Senior Research Fellow Matti Kinnunen and Senior Research Fellow Tapio Fabritius, Optoelectronics and Measurement Techniques laboratory, Department of Electrical Engineering, University of Oulu
risto.myllyla(at)ee.oulu.fi, matti.kinnunen(at)ee.oulu.fi, tapio.fabritius(at)ee.oulu.fi
http://www.infotech.oulu.fi/negoma

 

Background and Mission

NeGOMA group focuses on development of solution processable components and systems (sensors and sensor networks, light sources, light detectors, optical components etc) for different kinds of measurement applications. The motivation is to find new ways of applying the new generation optoelectronics to generate high level scientific knowledge but also find solutions which have a real commercial potential in industry and health care. In addition, NeGOMA group members investigate and develop different measurement methods for various applications. NeGOMA group is an active member in PrintoCent as well as a member in More-than-Moore (MtM) RAE consortium. MtM succeeded well in the evaluation, getting 6/6 points in the Vidi category.  

The wellness and health costs in developed countries are increasing continually. Rapid diagnostics has been seen as one solution to lower the costs. There is a need for an easy to use sensing platform which could be exploited at the doctor’s office and in home care. In this study optical polymer detection platforms will be integrated with microfluidic sample handling systems. The aim is to develop an integrated optofluidic sensor platform which meets the criteria for a disposable low cost device with possibility for high throughput manufacturing.

The other direction of current research is investigation of plasmon resonant gold nanoparticles (PRNPs) with variable morphology as contrast agents for optical coherence tomography and confocal microscopy.

 

Scientific Progress

An Integrated Optofluidic Sensor Platform

With this study period surface enhanced Raman scattering (SERS) substrates have been integrated with microfluidic sample transport systems. Used SERS substrates have been roll to roll fabricated by UV nanoimprint technique. Gold layer needed for the SERS effect has been evaporated on top of the SERS surface. Microfluidic transport system has been made by plotter cutting the channel shapes on adhesive layers. Microfluidic lid has been made from optically clear fluorescence minimized polyolefin adhesive.

Functionality of this optofluidic sensor has been studied with Raman active Rhodamine 6G sample molecules with different flow velocities and different concentrations under a Raman microscope. In Figure 1 the trial set-up has been depicted and in Figure 2 is a close up of the optofluidic SERS chip in the set-up.

Figure 1. Trial set-up system for Rhodamine 6G flow studies.

 

Figure 2. Close up picture of the optpfluidic SERS chip.

 

The effect of the Rhodamine sample arriving at the sensing surface can be seen as a function of time in Figure 3.

Figure 3. Arrival of the Rhodamine 6G molecules as a function of time to the sensing surface.

 

From the relationship between flow velocity and signal rise times we can see the time needed for the molecule in the flow to reach the sensing surface and on the other hand the lag time of the SERS detection itself.

Gold Nanoparticles for Optical Imaging

Plasmon resonant gold nanoparticles with variable morphology were fabricated and characterized. The absorption and scattering components of the plasmonic spectrum were estimated; the latter is essential for bioimaging and diagnostics. The ratio between scattering and absorption coefficients of nanostructures were evaluated from collimated transmittance and diffuse reflectance/transmittance measurements by the spectrophotometer system with integrating spheres. Figure 4 demonstrates extinction, absorption and scattering coefficients of nanostars (NSts) with diameter of 100 nm.

Figure 4. Extinction (µext), scattering (µsct) and absorption (µabs) coefficients of NSts suspensions of retrieved from spectrophotometric measurements.

 

We performed experiments for optical coherence tomography (OCT) capillary flow visualization of the small pristine and silica-coated nanostars (50 nm diameter) with different silica shell thickness. The most intensive OCT signal was registered from the suspensions with the thickest silica shells. The large nanostars (diameter more than 82 nm) showed excellent scattering properties in OCT and Doppler OCT. Figure 5 depicts reconstructed velocity profiles for the suspensions of NSts with diameter 82 nm, NSts with diameter 100, NSts with diameter 120 and Itralipid-4% model profile.

Figure 5. Reconstructed velocity profiles for the suspensions of NSts-82, NSts-100, NSts-120 and Intralipid-4%.

 

Treatment ability of the synthesized nanostructures was demonstrated by laser-assisted cell optoporation – generation transient pores in the cell membrane. The as-prepared and functionalized PRNPs of different morphology were used for cell optoporation. The cells were irradiated by a CW or nanosecond lasers in presence of PRNs for enhanced membrane permeabilization and more successful penetration of nanostructures into the cells. We assayed the effect of laser parameters and morphology of different PRNPs on viability of cells and their permeability for extracellular substances (fluorescent markers).

We tested the method of real-time visualization of PRNPs by analyzing the backscattering signal of nanospheres, nanostars and nanocomposites obtained with conventional laser confocal microscope both in agarose and in living cells. Observation of living cells, incubated with gold nanostructures by confocal microscopy allows monitoring of PRNPs uptake and localization in real time (Figure 6). We applied conventional laser confocal microscopy in combined scattering and transmission light modes to eliminate the back-scattering signal of gold nanoparticles. For the detection of PRNPs backscattering the signal acceptance band was superposed with the exciting laser wavelength.

Figure 6. Medial slides of cells with NSts. The NSts are concentrated inside cells (red arrows).

 

NeGOMA group people participated in several conferences and presented their results during year 2014. These conferences include international and national conferences, for example: The International Conference “Biophotonics: Photonic Solutions for Better Health Care” in frames of SPIE Photonics Europe (Brussels, Belgium), 10th International young scientist conference “Developments in Optics and Communications”, Laserlab III Training school "Laser Applications in Spectroscopy, Industry and Medicine" (Riga, Latvia), The International School for Junior Scientists and Students on Optics, Laser Physics and Biophysics “Saratov Fall Meeting, SFM’14” (Saratov, Russian Federation), Advanced Optical Materials and Devices (AOMD-8) (Latvia, 2014), and Optics and Photonics Days (Finland, 2014).

In SPIE Photonics Europe conference, Ms. Bibikova was awarded with the Biophotonics Award for Best Poster Contribution. Olga received the award for her poster entitled "Gold nanostructures for optical coherence tomography imaging of blood flow".

 

Personnel

professors

2

senior research fellows

3

postdoctoral researchers

7

doctoral students

11

other research staff

4

total

27

person years for research

20

 

External Funding

Source

EUR

Academy of Finland

82 000

Tekes

274 000

international

22 000

total

378 000

 

Doctoral Theses

Sliz, R (2014) Analysis of wetting and optical properties of materials developed for novel printed solar cells. Acta Universitatis Ouluensis, Technica C 492.

Myllylä, T (2014) Multimodal biomedical measurement methods to study brain functions simultaneously with functional magnetic resonance imaging. Acta Universitatis Ouluensis, Technica C 497.

 

Selected Publications

[1] O. Bibikova, A. Popov, A. Bykov, A. Prilepskyii, M. Kinnunen, K. Kordas, V. Bogatyrev, N. Khlebtsov, and V. Tuchin, “Gold nanostructures for OCT imaging of capillary flow,” Proc. SPIE 9129, Biophotonics: Photonic Solutions for Better Health Care IV, 912930 (2014).

[2] M. Kinnunen, A. Karmenyan, A. Särkelä, E. Y. Dimova, and T. Kietzmann, ” Low-intensity light   detection methods for selected biophotonic applications,” Proc. SPIE, 9421, 94210D (2014).

[3] M. Kinnunen, A. Bykov, J. Tuorila, T. Haapalainen, A. Karmenyan, and V. Tuchin, ”Optical clearing at a cellular level,” Journal of Biomedical Optics 19(7), 071409  (2014).

 

Last updated: 2.6.2016