Transcript Suspended Microchannel Resonator

Suspended Microchannel Resonator
(SMR) for Improved Mass Detection
PhD Student: Celso Accoto – ID: 31130, year II
Tutors: Prof. F. Pirri/Prof. C. Ricciardi (Politecnico di Torino)
Prof. M. De Vittorio/Dr. F. Rizzi (IIT – CBN)
Outline
q  Attended classes
q  Research Context and Motivation: Bio–mechanical sensor for liquid
chemical analyses
q  Addressed research problems: Fabrication complexity
q  Novel contributions:
q 
Direct writing on Photoresist by Two–photon Lithography
q  Adopted methodologies: Design, Manufacturing, Testing
q  Submitted and published conference/journal papers
q  Future work
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Attended classes from 01 March 2013 to 31 December 2014
Total of academic courses: 930
hours in distance learning!
!
(From the call for the "PONa3_00077, Infrastructure
Project for bio-MEMS Technologies for Advanced
Sensing of Environmental and Food Monitoring and
Diagnostics”)!
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Motivation
Ø Mechanical biosensors can provide high mass
resolution in both vacuum and air
Ø  Frequency-shift-based mass detection operating in Dynamic
mode requires resonators with high vibrational quality
factors (Q)
Ø  Quality factor degrades in fluid operation
§  poor sensitivity performances
Image source: Tamayo et al., Chemical Society Reviews, 2013, 42
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Addressed research problems
Ø  Suspended Microchannel Resonator (SMR) with
functionalized inner channels for the liquid flow can operate
in vacuum at very high quality factors (Burg, 2007)!
!f
!m = "2 # meff
f0
Ø  Internal channel for liquid flow!
Ø  High–Q condition is restored!
Image source: Tamayo et al., Chemical Society Reviews, 2013, 42
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Novel contributions
Ø  Fabrication of a resonating microfluidic channel in SU8 epoxy
resin combined with Laser Doppler measurement technique
Ø  Exploiting of a Two–photon Direct Laser Writing (DLW) technique
Ø  The internal channel can be nano-structured
Ø  Increase in the Surface–to–Volume ratio (S/V)
Ø  Improved sensitivity for mass detection
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Adopted methodologies: 3D Lithography
ü  Few steps of fabrication!
ü  Fully automatic processing!
ü  Sensor reproduced with high reliability !
Piezo stage volume:!
300×300×300µm3!
ü  Sub–μm Resolution (100nm)!
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Adopted methodologies: First Design and FEM Simulations
Ø  Resonating microfluidic channel geometry:
Ø  Channel Length: 100µm
Ø  Internal channel section: 10µm × 10µm
v  Resonant frequency range: 0,2 to 2,06 MHz
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Adopted methodologies: Second Design and FEM Simulations
Ø  Resonating microfluidic channel geometry:
Ø  Channel Length: 200µm
Ø  Internal channel section: 20µm × 20µm
Liquid tank!
SU8!
SMR!
SU8!
70 µm!
GLASS!
v  1st Flexural Resonant frequency: 898 kHz in vacuum, 881 kHz in air
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Adopted methodologies: Writing process optimization
Ø Array of cubes written in SU–8 with
different wall thickness for porosity test
1µm
2µm
3µm
Laser Power: 6mW, Writing speed: 20µm/s
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Adopted methodologies: SEM inspection – First Design
Internal
channel
Adopted methodologies: SEM inspection – Second Design
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Adopted methodologies: Laser Doppler Vibrometry tool for
Device Characterization
Ø Resonant frequency: Measurement set–up
²  Polytech Vibrometer!
MSA 500!
²  Detail on the piezoelectric
disc carrying the DUT!
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Adopted methodologies: Laser Doppler Vibrometry tool for
Device Characterization
Ø 1st Flexural Resonant frequency in air measurements is 880 kHz
in agreement with the simulation value
v Software reconstruction of the
1st Flexural Resonant
frequency in air: the highest
displacement is in the centre
of the suspended beam
Q ~ 60 in air
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Submitted and published conference/journal papers
Ø  Oral presentation at the 39th International Conference on
Micro and Nano Engineering, London 16 – 19 September
2013
“Two-photon direct laser writing in SU8 epoxy resin of a suspended microchannel resonant biomechanical sensor for liquid chemical analyses”!
C. Accoto, A. Qual-eri, F. Pisanello, C. Ricciardi, F. Pirri, M. De Vi:orio, F. Rizzi
Ø  XIV Giornata Mondiale dell’Acqua: Convegno “Gestione Sostenibile del
Mediterraneo” at Accademia Nazionale dei Lincei, Rome 21 March 2014
“Litografia Laser a due fotoni per la fabbricazione di sensori bio-meccanici microfluidici per la
diagnostica chimica di inquinanti in liquido”!
F. Rizzi, C. Accoto, S. Stassi, S. Marasso, A. Qual-eri, F. Pisanello, C. Ricciardi, F. Pirri, M. De Vi:orio
Ø  In press: paper at the IEEE Journal of Microelectromechanical System,
October 2014
“Two-Photon Polymerization Lithography and Laser Doppler Vibrometry of a SU-8-based
Suspended Microchannel Resonator”!
C. Accoto, A. Qual-eri, F. Pisanello, C. Ricciardi, F. Pirri, M. De Vi:orio, F. Rizzi C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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Future work
Ø  Sensitivity can be boosted by nano–structuring the internal
channel
Ø  Functionalization experiments through Parylene coating
Ø  Definition and implementation of a read–out technique
Ø  Optical detection
Ø  Piezoelectric/piezoresistive detection
C. Accoto ”Suspended Microchannel Resonator (SMR) for Improved
Mass Detection”!
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