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Integrated optical read-out for polymeric cantilever-based sensors

Tenje, Maria LU (2007)
Abstract (Swedish)
Popular Abstract in Undetermined

Denne afhandling præsenterer en ny udlæsnings metode udviklet til cantileverbaserede sensorer. Cantilevere er tynde vipper, der er fastgjorte i den ene ende, og som igennem de seneste ti °ar har vist sig at være en interessant ny type bio/kemisk sensor. Den specifikke genkendelse af et kemikalie viser sig ved at cantileveren bøjer som følge af det skabte overfladestress. Traditionelt bliver denne krumning kontrolleret af den eksterne optiske udlæsnings metode kendt fra atomic force mikroskopet (AFM). Et s°adant set-up er dog meget stort. Det er derfor gavnligt at fremstille et formindsket system. Desuden opn°as forøget følsomhed ved at fremstille cantileveren af et plastiskt materiale med et... (More)
Popular Abstract in Undetermined

Denne afhandling præsenterer en ny udlæsnings metode udviklet til cantileverbaserede sensorer. Cantilevere er tynde vipper, der er fastgjorte i den ene ende, og som igennem de seneste ti °ar har vist sig at være en interessant ny type bio/kemisk sensor. Den specifikke genkendelse af et kemikalie viser sig ved at cantileveren bøjer som følge af det skabte overfladestress. Traditionelt bliver denne krumning kontrolleret af den eksterne optiske udlæsnings metode kendt fra atomic force mikroskopet (AFM). Et s°adant set-up er dog meget stort. Det er derfor gavnligt at fremstille et formindsket system. Desuden opn°as forøget følsomhed ved at fremstille cantileveren af et plastiskt materiale med et lavt Youngs modulus i stedet for af de traditionelle materialer Si og Si3N4. En ny udlæsning metode præsenteres her, hvor optiske bølgeledere bruges til at integrere lys i cantileveren. Det er et af plast fremstillet apparat, hvor b°ade cantilevere og bølgeledere er fremstillet i det negative resist SU-8. Bølgeledere er strukturer p°a begge sider af en cantilever, der hænger frit i en mikrofluid kanal. Lys ledes ind i systemet og bliver enten overført gennem cantileveren eller kastet tilbage fra frontdelen af cantileveren, afhængig af fremgangsm°aden. Denne afhandling viser at bølgeledere som kun understøtter den fundamentale mode ved 1 310 nm og med et udbredelsestab p°a kun 1.2 dB/cm kan fremstilles og integreres med frit-hængende cantilevere. En teoretisk model er blevet udviklet til at analysere følsomheden ved de to forskellige udlæsningsmetoder. Baseret p°a kalibreringseksperimenter bliver det mindst sporbare cantilever-udslag i transmissionsm° aden m°alt til 45 nm, hvilket passer fint med den beregnede værdi p°a 30 nm. Proof-of-principle vises ogs°a for refleksionsmetoden men ingen endegyldig værdi kan bestemmes for udlæsningsfølsomheden. (Less)
Abstract
This thesis presents a novel read-out method developed for cantilever-based sensors. Cantilevers are thin beams clamped at one end and during the last 10 years they have emerged as an interesting new type of bio/chemical sensor. The specific recognition of a chemical manifests itself as a bending of the cantilever from the generated surface stress. Conventionally the read-out used for this type of sensors is external and thereby very bulky. It is beneficial to fabricate a miniaturised system. Moreover, improved sensitivity is obtained by fabricating the cantilever in a polymeric material that has a low Young’s modulus instead of the conventional materials Si and Si3N4. Here, a novel read-out method is presented where optical waveguides are... (More)
This thesis presents a novel read-out method developed for cantilever-based sensors. Cantilevers are thin beams clamped at one end and during the last 10 years they have emerged as an interesting new type of bio/chemical sensor. The specific recognition of a chemical manifests itself as a bending of the cantilever from the generated surface stress. Conventionally the read-out used for this type of sensors is external and thereby very bulky. It is beneficial to fabricate a miniaturised system. Moreover, improved sensitivity is obtained by fabricating the cantilever in a polymeric material that has a low Young’s modulus instead of the conventional materials Si and Si3N4. Here, a novel read-out method is presented where optical waveguides are used to integrate the light into the cantilever. It is an all-polymer device where both the cantilever and the waveguides are fabricated in the negative resist SU-8. Waveguides are structured on either side of the cantilever that is free-hanging in a microfluidic channel. Light is guided into the system and is either transmitted through the cantilever or reflected off the cantilever front-end, depending on the mode of operation. This work shows that waveguides, only supporting the fundamental mode at 1 310 nm and with a propagation loss of only 1.2 dB/cm can be fabricated and integrated with free-hanging cantilevers. A theoretical model is developed to analyse the read-out sensitivity of the two different read-out modes. From calibration experiments the minimum detectable cantilever deflection in the transmission mode is measured as 45 nm, which compares well with the calculated value of 30 nm. Proof-of-principle is shown for the reflection mode as well but no conclusive value can be determined for the read-out sensitivity. It is believed both these novel principles present interesting alternatives for integrated read-out for cantilever based sensors to enable to fabrication of point-of-care analysis systems. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof Nordin, Gregory P., Brigham Young University, USA
  • Dr.Ing. Ruano-López, Jesús, Microsystems Area, IKERLAN, Spain
publishing date
type
Thesis
publication status
published
subject
pages
157 pages
publisher
MIC - Department of Micro and Nanotechnology, Technical University of Denmark
defense location
DTU
defense date
2007-05-16 13:00
language
English
LU publication?
no
id
f2e5d29b-0e88-4ab7-a2ba-c57e4980e24f (old id 3128884)
date added to LUP
2012-10-12 14:38:33
date last changed
2016-09-19 08:45:06
@misc{f2e5d29b-0e88-4ab7-a2ba-c57e4980e24f,
  abstract     = {This thesis presents a novel read-out method developed for cantilever-based sensors. Cantilevers are thin beams clamped at one end and during the last 10 years they have emerged as an interesting new type of bio/chemical sensor. The specific recognition of a chemical manifests itself as a bending of the cantilever from the generated surface stress. Conventionally the read-out used for this type of sensors is external and thereby very bulky. It is beneficial to fabricate a miniaturised system. Moreover, improved sensitivity is obtained by fabricating the cantilever in a polymeric material that has a low Young’s modulus instead of the conventional materials Si and Si3N4. Here, a novel read-out method is presented where optical waveguides are used to integrate the light into the cantilever. It is an all-polymer device where both the cantilever and the waveguides are fabricated in the negative resist SU-8. Waveguides are structured on either side of the cantilever that is free-hanging in a microfluidic channel. Light is guided into the system and is either transmitted through the cantilever or reflected off the cantilever front-end, depending on the mode of operation. This work shows that waveguides, only supporting the fundamental mode at 1 310 nm and with a propagation loss of only 1.2 dB/cm can be fabricated and integrated with free-hanging cantilevers. A theoretical model is developed to analyse the read-out sensitivity of the two different read-out modes. From calibration experiments the minimum detectable cantilever deflection in the transmission mode is measured as 45 nm, which compares well with the calculated value of 30 nm. Proof-of-principle is shown for the reflection mode as well but no conclusive value can be determined for the read-out sensitivity. It is believed both these novel principles present interesting alternatives for integrated read-out for cantilever based sensors to enable to fabrication of point-of-care analysis systems.},
  author       = {Tenje, Maria},
  language     = {eng},
  pages        = {157},
  publisher    = {ARRAY(0x93242d0)},
  title        = {Integrated optical read-out for polymeric cantilever-based sensors},
  year         = {2007},
}