Universidade do Minho
Escola de Engenharia
Dept. Electrónica Industrial
Este trabalho foi financiado por fundos nacionais através da FCT - Fundação para a Ciência e a Tecnologia, referência do projecto PTDC/BIO/70017/2006, e co-financiado pelo FEDER, através do Eixo I do Programa Operacional Fatores de Competitividade (POFC) do QREN, referência COMPETE: FCOMP-01-0124-FEDER-007088.
Título: “Laboratorio num chip com microagitação acústica dos fluidos”. Duração do projecto: Julho de 2007 a Dezembro de 2010. Entidade financiadora: Fundação para a Ciência e a Tecnologia PTDC/BIO/70017/2006 (financiamento 83 000,00 €).
Title: "Lab-on-a-chip with fluidic acoustic microagitation". Project duration: July 2007 to December 2010. Funding: FCT - PTDC/BIO/70017/2006 (budget 83 000,00 €).
Abstract:
Microfluidic technology has become a vital tool for analytical biochemistry applications. It enables the fabrication of precise and small structures in glass, quartz, silicon or polymeric materials: the lab-on-a-chip concept. The great interest in that technology stems from the inherent performance gains: reduced sample size, higher degree of integration and thus enhanced potential for automation and control fluids of submicroliter volumes, shortened response time, potential for improved analytical performance, reduced chemicals storage and hence laboratory safety and reduced costs.
There is a large demand in the healthcare system to develop lab-on-a-chips for rapid and reliable point of care (POC) testing and monitoring. Such lab-on-a-chips would significantly enhance the quality of a diagnostic, by offering immediate measurement of several clinically relevant parameters that can be used to assess patient’s health. The biochemical analysis of patient’s biological fluids is a good start. Most diseases leave a molecular fingerprint in those fluids and by measuring that fingerprint in the right way, the precision of the diagnostic can be increased. Once the physician or the patient have no routine in performing the advanced biochemical analysis on-chip, to develop point of care disposable lab-on-a-chips (avoiding crosscontamination of samples and measurements errors) is necessary to have a reliable and highly automated microfluidic control system. This system should be fully integrated with the control and the detection electronics that can be implemented on a low-cost substrate and by a low-cost fabrication process. The use of MEMS (Micro Electro Mechanical Systems) based devices such as microvalves and micropumps increases the cost of the system, needs complex control systems and are difficult to integrate. Mixing only by diffusion avoids these drawbacks. However, when large molecules with small diffusivities must react, it is needed long transit time and consequently long microchannels. This illustrates how dramatic diffusion limitation is. To overcome the long transit times due by diffusion and to enable high-efficient reactions it is necessary to indue the microfluidic die by a mechanism that accelerates the mixing and reaction, with no moving parts.
This proposal is about the realization of a portable, low-cost, plastic based, disposable, high automated lab-on-a-chip capable of performing biochemical analyses in biological fluids for being applicable in point of care systems using fluids acoustic microagitation and using absorbance and fluorescence detection techniques.
The lab-on-a-chip is composed by two dies: the microfluidic die and the detection die. The microfluidic die includes the microchannels and the reaction chambers. It also should include on-chip storage of reagents/buffers/controls such that the lab-on-a-chip will be a self-contained unit. It is fabricated using a photoplastic material (SU-8). The channels and the reaction chambers are coated by a piezoelectric polymer (beta-PVDF), for the occurrence of the fluids acoustic microagitation. The coated beta-PVDF is subjected to an electrical field of tens of megavolts by meter, which is known as the electrical polarization of the polymeric material process. After this step, electrical contacts are deposited on the beta-PVDF. This structure will produce the needed vibration along the channels. By applying electrical alternating voltages gradient to the electrical contacts of the beta-PVDF along the microchannels and the reaction chambers, mechanical oscillations are produced which improve the motion, the mixing and the reaction. The reaction chambers includes, besides the beta-PVDF for the microagitation, a platinum resistor deposited using physical vapor deposition. This resistor has two main objectives: heating the chamber by applying an electrical current and sensing the chamber temperature by measuring its electrical resistance.\nThe detection die includes the detectors and the electronics for signals actuation and detection, all fabricated in CMOS technology. Specifically, it comprises the photodetectors, its readout electronics and the electronics that control the phase of the voltages applied to the beta- PVDF. On this die, and above the photodetectors, there are several high-selective band-pass optical filters, deposited by Ion Beam Deposition, that select the wavelength according to the several biomolecules into analysis. This optical filtering system allows the use of a non-calibrated external polychromatic light illumination source, such as a lamp connected to the power supply, being the reliability of the measurements assured by the fact that the lab-on-a-chip compensates the fluctuations associated to the use of those light sources, detecting simultaneously the optical signals of: the fluid samples; the baseline reference; and the calibration control. The bonded die will be as low as 5 x 5 x 1 mm3.
Results:
From the scientific point of view the results show clear the high scientific quality, e.g., it can be seen by the publications: 6 Papers in international journals; 19 Communications in international meetings.
The project has contributed for the formation of young researchers: 2 PhD thesis and 7 master thesis, and for the international projection of the involved team.
The main achieved objectives are described, without entering in details once they were already published:
- Development and evaluation of a lab-on-a-chip for point of care monitorization of several parameters in biological fluids.
- Application and evaluation of the acoustic microagitation technique (specifically acoustic streaming) by the deposition of a piezoelectric beta-PVDF under the microstructures.
- Control of the signals applied to the beta-PVDF, in terms of frequency and amplitude, resulting in the microfluids mixing control.
- Development of the computational simulations that relate the mechanics vibration produced by the beta- PVDF with the fluids movement allowing the acoustic thermoagitation.
- Development of the optical filters co-integrated in CMOS, which gives portability to the lab-on-a-chip.
- Characterization of the SU-8 microstructures
- Processing and characterization of the beta-PVDF
- Processing PDMS microstructures
From the technological point of view:
- Implemented a system for SU-8 microstructures fabrication
- Implemented a system for PDMS microstructures fabrication
- Optimized the system for deposition of the PVDF by spin coating
- Implemented a system for spectrofotometric measurements by optical absorption
Some illustrations:
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Distribution of the fluid vertical velocity and the mechanical displacement.
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| Schematic representation of the lab-on-a-chip device with β-PVDF based acoustic streaming. |
SEM micrograph of the β-PVDF film. |
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A photograph of the CMOS chip. |
Photograph of the tested lab-on-a-chip with microfluidic die glued on the top of the CMOS die. |
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| Reaction time vs frequency, for a 5 mg/dl of uric acid concentration in urine, when a sinusoidal signal of 10 V amplitude is applied to the β-PVDF film. | Reaction time vs amplitude, for a 5 mg/dl of uric acid concentration in urine, when a sinusoidal signal of 10 MHz frequency is applied to the β-PVDF film. |
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Measured absorbance at 550 nm for 5 mg/dl of uric acid concentration in urine as function of time, obtained by applying acoustic streamig with a 10 V and 10 MHz electrical signal to the β-PVDF film (b), and by heating a fluid sample with the same temperature profile with a temperature controller (c). Curve (a), inset, presents the generated heating by the β-PVDF film. |
Publications:
Papers in international journals:
A. V. Fernandes, V. F. Cardoso, J. G. Rocha, J. Cabral, G. Minas - Smart-Optical Detector CMOS Array for Biochemical Parameters Analysis in Physiological Fluids. In IEEE Transactions on Industrial Electronics, Vol. 55, N.9 (2008), p. 3192-3200.
V.F. Cardoso, P. Martins, J. Serrado Nunes, L. Rebouta, J. G. Rocha, G. Minas, S. Lanceros-Méndez - Ultrasonic Transducer based on beta-PVDF for Fluidic Microagitation in a Lab-on-a-Chip device. BIOMEDICAL APPLICATIONS OF SMART MATERIALS, NANOTECHNOLOGY AND MICRO/NANO ENGINEERING, In Advances in Science and Technology Vol. 57 (2008) p. 99-104.
V F Cardoso, S O Catarino, J S Nunes, L Rebouta, J G Rocha, S. Lanceros-Méndez, G Minas, Lab-on-a-chip with β-PVDF based acoustic microagitation. In IEEE Transactions on Biomedical Engineering, IEEE, Vol. 57, N5 (2010), p. 1184-1190.
G. Minas, R. F. Wolffenbuttel, J. H. Correia - MCM-based microlaboratory for simultaneous measurement of several biochemical parameters by spectrophotometry. In Biomedical Microdevices, Springer US, Vol. 12, N4 (2010), p. 727–736.
J. M. Miranda, H. Oliveira, J. A. Teixeira, A. A. Vicente, J. H. Correia, G. Minas - Numerical study of micromixing combining alternate flow and obstacles. In International Communications in Heat and Mass Transfer, Elsevier, Vol. 37 (2010), p. 581–586.
V. F. Cardoso, P. Martins, G. Botelho, L. Rebouta, S. Lanceros-Méndez, G. Minas - Degradation studies of transparent conductive electrodes on electroactive poly(vinylidene fluoride) for uric acid measurements. In Science and Technology of Advanced Materials, IOP, Vol.11, N4 (2010), p. doi: 10.1088/1468-6996/11/4/045006.
International conference proceedings:
H. Oliveira, J. M. Miranda, J. A. Teixeira, A. A. Vicente, J. H. Correia, G. Minas; ALTERNATE FLOWS IN A MICROFLUIDIC DEVICE; In proceedings of MME 2007, MicroMechanics Europe Workshop; p. 379-382; 16-18 September 2007, Guimarães, Portugal.
V. F. Cardoso, J. G. Rocha, F. O. Soares, G. Minas, S. Lanceros-Mendez – Lab-on-a-chip with fluid acoustic microagitation: Piezoelectric Polymer ß-PVDF Used as Ultrassonic Transducer. In “Proceedings of BioDevices 2008 – The International Conference on Biomedical Electronics and Devices”, Madeira, Portugal, 28-31 Janeiro 2008, p. 262-267.
Pedro Martins, V.F. Cardoso, J. Serrado Nunes, S. Lanceros-Mendez, J. H. Correia, G. Minas - Electroactive ß-PVDF Polymer as Fluidic Acoustic Mixer for Lab-on-a-Chip Applications. In Proceedings of NanoSpain 2008 – NanoIberian Conference, Braga, Portugal, 14-18 Abril de 2008.
B. Silva, J.G. Rocha, A. J. Ferreira, S.Lanceros-Mendez, G.Minas - Tunable Fabry-Perot Optical Filter with a Resonant Cavity Based on a Piezoelectric Polymer. In Proceedings of NanoSpain 2008 – NanoIberian Conference, Braga, Portugal, 14-18 Abril de 2008.
V. F. Cardoso, J. G. Rocha, J. Serrado Nunes, S. Lanceros-Mendez, G. Minas - Piezoelectric beta-PVDF Polymer Films as Fluid Acoustic Microagitator. In Proceedings of ISIE 2008, Cambridge, UK, 30 Junho a 2 Julho 2008, p. 2028-2033.
V.F. Cardoso, P. Martins, J. Serrado Nunes, L. Rebouta, J. G. Rocha, S. Lanceros-Mendez, G. Minas – Lab-on-a-chip with beta-PVDF based acoustic microagitation. In Proceedings of The 22nd International Conference EUROSENSORS 2008, Dresden, Germany, 07-10 September 2008, p.727-730.
P. Martins, V. F. Cardoso, J. Serrado Nunes, L. F. Rebouta, J. G. Rocha, G. Minas, S. Lanceros-Méndez - A Lab-on-a-Chip for Clinical Analysis with Acoustic Microagitation based on Piezoelectric Poly(vinilidene fluoride), In “MRS2008 – Materials Research Society: Fall Meeting”, Boston, MA, USA, 1-5 December 2008, p. 1-6.
V. F. Cardoso, G. Minas, P. Martins, J. Serrado Nunes, L. Rebouta, S. Lanceros-Méndez, G. Botelho – Acoustic thermoagitation based on piezoelectric beta-PVDF polymer films: Potential Evaluation in Lab-on-a-Chip Applications, In “Proceedings of BioDevices 2009 – The International Conference on Biomedical Electronics and Devices”, Porto, Portugal, 14-17 Janeiro 2009, p. 394-397.
J. M. Miranda, J. A. Teixeira, A. A. Vicente, J. H. Correia, Member, IEEE, G. Minas - Improving Alternate Flow mixing by Obstacles Located along a Micro-Channel, In Proceedings of EMBC2009 - the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Hilton Minneapolis, Minnesota, USA, 2-6 September, 2009, p. 7034-7036.
V. F. Cardoso, S. O. Catarino, P. Martins, L. Rebouta, S. Lanceros-Mendéz, G. Minas – Biological Microdevice with fluidic acoustic streaming for measuring uric acid in human saliva, In Proceedings of EMBC2009 - the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Hilton Minneapolis, Minnesota, USA, 2-6 September, 2009, p. 5879-5882.
J. G. Rocha, V. Cardoso, S. Lanceros Mendez, G. Minas - Piezoelectric micropump for lab-on-a-chip applications, In ICM 2009 - 21th International Conference on Microelectronics, Marrakech, Morocco, 19-22 December, 2009, p. 404-407.
S. O. Catarino, J. G. Rocha, S. Lanceros-Mendéz, R. G. Correia, V. F. Cardoso, G. Minas - Heating of samples by acoustic microagitation for improving reaction of biological fluids, In Proceedings of ISIE2010, Bari, Italy, 4-7 July, 2010, p. 446-451.
S. Reis, V. Correia, M. Martins, G. Barbosa, R. M. Sousa, G. Minas, S. Lanceros-Mendez, J. G. Rocha - Touchscreen based on acoustic pulse recognition with piezoelectric polymer sensors, In Proceedings of ISIE2010, Bari, Italy, 4-7 July, 2010, p. 516-520.
S. Reis, V. Correia, M. Martins, G. Barbosa, R. M. Sousa, G. Minas, S. Lanceros-Mendez, J. G. Rocha - Precise duty-cycle measurement for time of transit ultrasound flowmeters, In Proceedings of ISIE2010, Bari, Italy, 4-7 July, 2010, p. 3366-3370.
V. F. Cardoso, R. G. Correia, J. G. Rocha, S. Lanceros-Mendéz, G. Minas – Design and fabrication of piezoelectric microactuators based on β-poly(vinylidene fluoride) films for microfluidic applications, In Proceedings of EMBC2010 - the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Buenos Aires, Argentina, August 31 - September 4, 2010, p. 903-906.
V.F. Cardoso, C.M. Costa, S. Lanceros-Méndez, G. Minas – Micro and Nanofabrication of beta-Poly(Vinylidene Fluoride) sensors and actuators, In 3rd International Conference on Advanced Nano Materials, Agadir, Morocco, 12-15 September 2010, p1.
V.F. Cardoso, G. Minas, S. Lanceros-Méndez – Functionally graded electroactive Poly(Vinylidene Fluoride) by multilayer spin-coating deposition with controlled crystalline phase content, In 11th International Symposium on Multiscale, Multifunctional and Functionally Graded Materials, Guimarães, Portugal, 26-29 September 2010, p. 112.
C. Martins, J. Borges, L. Cunha, F. Vaz, G. Minas – Aluminium oxynitride thin films based optical filter for biomolecules analysis in biological fluids, In 11th International Symposium on Multiscale, Multifunctional and Functionally Graded Materials, Guimarães, Portugal, 26-29 September 2010, p. 192.
Susana O. CATARINO, João M. MIRANDA, Senentxu LANCEROS-MENDEZ, Graça MINAS - Modeling and simulation of the Mixing process in microfluidic channels promoted by acoustic streaming, To be published in 3rd Micro and Nano Flows Conference, Thessaloniki, Greece, 22-24 August 2011.
National conference proceedings:
V. F. Cardoso, S. O. Catarino, S. Lanceros-Mendez, G. Minas - Lab-on-a-chip using acoustic streaming for for mixing and pumping fluids – In 1º Encontro Nacional de Bioengenharia, Campus Taguspark do Instituto Superior Técnico, Oeiras, Portugal, 1-4 Março 2011, p. 76-79.