Compact On-chip Multiplexed chip Multiplexed ... - OSA Publishing
JW2A.74.pdf
CLEO:2013 Technical Digest © OSA 2013
Compact On-chip chip Multiplexed Photonic Gas Sensors Zhixuan Xia1, Ali Asghar Eftekhar1, David S. Gottfried2, Qing Li1, Ali Adibi1 1.
School of Electrical and Computer Engineering, Georgia Institute of Technology, 3033 30332 2. Institute for Electronics and Nanotechnology, Georgia Institute of Technology, 30332 [email protected]
Abstract: A compact resonator-based resonator based integrated photonic sensor for the detection of multiple gas analytes with high resolution is demonstrated. On-chip chip referencing is employed to compensate for environmental effects and laser instabilities to achieve high accuracy. OCIS codes: (280.4788) Optical sensing and sensors; (140.4780) Optical resonator Integrated photonic microresonator gass sensors have attracted a lot of attention for their high sensitivity, fast response, and ease of implementation [1-3]. [1 . The incoming gas analyte is detected via the refractive index change induced by the diffusion and adsorption of the gas molecules. Unlike their counterpart in biosensing applications, typical polymer-coated coated gas sensors suffer from a lack of selectivity and and specificity. To resolve this issue, an array of different polymers must be used to form a response matrix, as is widely done in the electronic nose technology [4] and recently demonstrated in micro-gas chromatography [5]. By carefully selecting a set of polymers with diverse properties, a response matrix with each row representing a unique signature for a certain gas analyte can be obtained. After obtaining this response matrix during data calibration, not only can the gas sensor identify a single unknown n incoming analyte, it can also potentially quantify a mixture of gas analytes. To simultaneously read the response from various polymers, an array of microring resonators is needed, where each of them is functionalized with a different polymer. Moreover, the radius of each microring resonator has to be small to increase the total number of resonators involved [6,7], leading to a large rank of the response matrix and hence better selectivity of the photonic gas sensor. In the integrated photonic gas sensor demonstrated in this paper, a total number of six resonators with slightly different resonance wavelengths are used. Four of these resonators are used as sensing elements and thus are covered by functional polymers. The polymers are applied with a commercial al inkjet printer using a 50 um diameter nozzle (Microfab Jetlab II). Since tthe microring resonators on a silicon-on-insulator insulator (SOI) substrate are very sensitive to temperature [8] and other environmental variations, the other two resonators are used as on on-chip reference to calibrate the measurement data. The on-chip on chip reference resonators are covered with SU SU-8 that is inert and impermeable to compensate for the effects of temperature variation and other environmental influences as well as any drift in the wavelength velength of the interrogating laser source [9]. To achieve high sensitivity, the microring microring resonator is designed to support a high quality factor (high (high-Q) TM-polarized polarized mode. The device layer is a 250 nm-thick nm thick silicon (Si) film, with a 1 µm thick buried oxi oxide layer underneath. The SEM image of an individual sensing resonator is shown in Fig. 1(a), where the outer radius of the microring resonator is ~ 4.3 µm to achieve a large free spectral range (FSR) while still maintaining a high loaded Q of ~ 40,000. The inner radius of the microring is ~ 3.6 µm to ensure single-mode single mode operation. The fabricated device is treated with a fluorosilane layer to increase its hydrophobicity before the polymer drop coating step. As is shown in Figs. 1(b) and (c), the fluorosilane treatment helps to remove the unwanted coffee ring effect and reduce the size of the polymer after evaporation of the solvent. This step significantly improves the repeatability and quality of the polymer coating. Fig. 2(a) is a micrograph of the multiplexed multiple gas sensor. In this study, resonators #1, #3, #4, and #6 are the four sensing resonators, which are coated with Poly(4-vinyl phenol) or PVP, Poly(vinylidene fluoride) or PVF, Poly(Vinyl acetate) or PVA, and a triptycene polyimide (polymer TPI1 in [10]),, respectively. respective The solvent used in this study is dimethyl imethyl sulfoxide (DMSO). Resonators #2 and #5 are used as on on-chip reference resonators to neutralize the temperature and other environmental effects,, which help to achieve a wavelength measurement accuracy of ±1 pm [7].
(b) (a) (c) Figure 1 (a) SEM of a single microring resonator; (b) pattern of dried PVP on substrate without fluorosilane treatment, where a coffee ring effect is clearly observed; (c) pattern of the dried PVP on substrate treated with fluorosilane.
JW2A.74.pdf
CLEO:2013 Technical Digest © OSA 2013
(a) (c)) (b) power Figure 2 (a) Micrograph of the multiplexed gas sensor; (b) transmission spectrum (i.e., transmitted power divided by the incident po in the bus waveguide in (a) for different wavelengths) of the gas sensor at TM polarization; (c) Image of the gas sensor sitting on the optical stage covered by a gas flow cell.
The transmission spectrum of the gas sensor is shown in Fig. 2(b). Each resonance is labeled with its corresponding resonator number.. The spacing between two neighboring resonances of resonator #5 is ~ 23 nm, which agrees well with the theoretical calculations of the FSR. The sensor is then integrated with a customized glass chamber and tested with gas analytes. Four volatile organic compounds, isopropanol isopropanol (IPA), methanol, benzene and acetone, were tested with the four selected s polymers. The he response pattern of the four analytes with respect to the four specified polymers is shown in Fig. 3, showing the normalized resonance wavelength drifts when each of the saturated gas analytes is injected. injected This data clearly shows the diversity in the response of the different polymer coatings to the different gas analytes. Further tests with additional polymers and target gas analytes are ongoing and a detailed ed discussion will be covered in the conference.
Figure 3 Normalized response patterns of the four test gas analytes with respect to the four polymers.
References [1] J. T. Robinson, L. Chen, M. Lipson, "On-chip chip gas detection in silicon optical microcavities,” microc Optics Express, 16,, 4296 4296-4301, (2008). [2] N. A. Yebo, P. Lommens, Z. Hens, R. Baets, "An integrated optic ethanol vapor sensor based on a silicon-on-insulator silicon insulator microring resonator coated with a porous ZnO film,"" Optics Express, 18, 11859-11866, (2010). [3] A. Ksendzov, M. L. Homer, A. M. Manfreda,, "Integrated optics ring-resonator ring resonator chemical sensor with polymer transduction layer," Electronics Letters, 40, 63-65, (2004). [4] P. C. Jurs, G. A. BakkenH. E. McClelland,, "Computational methods for the analysis of chemical sensor array data from volatile analytes," analytes Chemical Reviews, 100, 2649-2678, (2000). [5] K. Reddy, Y. B. Guo, J. Liu, W. Lee, M. K. K. Oo, X. D. Fan, “Rapid, sensitive, and multiplexed on-chip on chip optical sensors for micro micro-gas chromatography,” Lab on a Chip, 12, 901-905, (2012 2012) [6] Z. Xia, A. Eftekhar, M. Soltani, B. Momeni, Q. Li, M. Chamanzar, S. Yegananraynana, and A. Adibi, “High resolution on on-chip spectroscopy based on miniaturized microdonut resonators,” Optics Express, 19, 12356-12364, (2011) [7] Z. Xia, A. Eftekhar, Q. Li, and A. Adibi, “On--Chip Chip Multiplexed Photonic Gas Sensing for VOC Detection”, IPC 2012, San Francisco, CA, September 2012. [8] A. Alipour,, E. S. Hosseini, A. A. Eftekhar, B. Momeni, and A. Adibi, "Athermal performance in high-Q high polymer-clad clad silicon microdisk resonators," Optics Letter, 35, 3462-3464,, (2010). [9] D. X. Xu, M. Vachon, A. Densmore, ensmore, R. Ma, S. Janz, A. Delage, J. Lapointe, P. Cheben, J. H. Schmid, E. Post, S. Messaoudene, J. J.-M. Fedeli, "Real-time time cancellation of temperature induced reso resonance shifts in SOI wire waveguide ring resonator label-free free biosensor arrays," Optics Express, 18, 22867-22879, (2010). [10] S. A. Sydlik, Z. Chen, T. M. Swager,, “Triptycene Polyimides: Soluble Polymers with High Thermal Stability and Low Refractive Indices,” Macromolecules, 44, 976-980 (2011).
CLEO:2013 Technical Digest © OSA 2013
Compact On-chip chip Multiplexed Photonic Gas Sensors Zhixuan Xia1, Ali Asghar Eftekhar1, David S. Gottfried2, Qing Li1, Ali Adibi1 1.
School of Electrical and Computer Engineering, Georgia Institute of Technology, 3033 30332 2. Institute for Electronics and Nanotechnology, Georgia Institute of Technology, 30332 [email protected]
Abstract: A compact resonator-based resonator based integrated photonic sensor for the detection of multiple gas analytes with high resolution is demonstrated. On-chip chip referencing is employed to compensate for environmental effects and laser instabilities to achieve high accuracy. OCIS codes: (280.4788) Optical sensing and sensors; (140.4780) Optical resonator Integrated photonic microresonator gass sensors have attracted a lot of attention for their high sensitivity, fast response, and ease of implementation [1-3]. [1 . The incoming gas analyte is detected via the refractive index change induced by the diffusion and adsorption of the gas molecules. Unlike their counterpart in biosensing applications, typical polymer-coated coated gas sensors suffer from a lack of selectivity and and specificity. To resolve this issue, an array of different polymers must be used to form a response matrix, as is widely done in the electronic nose technology [4] and recently demonstrated in micro-gas chromatography [5]. By carefully selecting a set of polymers with diverse properties, a response matrix with each row representing a unique signature for a certain gas analyte can be obtained. After obtaining this response matrix during data calibration, not only can the gas sensor identify a single unknown n incoming analyte, it can also potentially quantify a mixture of gas analytes. To simultaneously read the response from various polymers, an array of microring resonators is needed, where each of them is functionalized with a different polymer. Moreover, the radius of each microring resonator has to be small to increase the total number of resonators involved [6,7], leading to a large rank of the response matrix and hence better selectivity of the photonic gas sensor. In the integrated photonic gas sensor demonstrated in this paper, a total number of six resonators with slightly different resonance wavelengths are used. Four of these resonators are used as sensing elements and thus are covered by functional polymers. The polymers are applied with a commercial al inkjet printer using a 50 um diameter nozzle (Microfab Jetlab II). Since tthe microring resonators on a silicon-on-insulator insulator (SOI) substrate are very sensitive to temperature [8] and other environmental variations, the other two resonators are used as on on-chip reference to calibrate the measurement data. The on-chip on chip reference resonators are covered with SU SU-8 that is inert and impermeable to compensate for the effects of temperature variation and other environmental influences as well as any drift in the wavelength velength of the interrogating laser source [9]. To achieve high sensitivity, the microring microring resonator is designed to support a high quality factor (high (high-Q) TM-polarized polarized mode. The device layer is a 250 nm-thick nm thick silicon (Si) film, with a 1 µm thick buried oxi oxide layer underneath. The SEM image of an individual sensing resonator is shown in Fig. 1(a), where the outer radius of the microring resonator is ~ 4.3 µm to achieve a large free spectral range (FSR) while still maintaining a high loaded Q of ~ 40,000. The inner radius of the microring is ~ 3.6 µm to ensure single-mode single mode operation. The fabricated device is treated with a fluorosilane layer to increase its hydrophobicity before the polymer drop coating step. As is shown in Figs. 1(b) and (c), the fluorosilane treatment helps to remove the unwanted coffee ring effect and reduce the size of the polymer after evaporation of the solvent. This step significantly improves the repeatability and quality of the polymer coating. Fig. 2(a) is a micrograph of the multiplexed multiple gas sensor. In this study, resonators #1, #3, #4, and #6 are the four sensing resonators, which are coated with Poly(4-vinyl phenol) or PVP, Poly(vinylidene fluoride) or PVF, Poly(Vinyl acetate) or PVA, and a triptycene polyimide (polymer TPI1 in [10]),, respectively. respective The solvent used in this study is dimethyl imethyl sulfoxide (DMSO). Resonators #2 and #5 are used as on on-chip reference resonators to neutralize the temperature and other environmental effects,, which help to achieve a wavelength measurement accuracy of ±1 pm [7].
(b) (a) (c) Figure 1 (a) SEM of a single microring resonator; (b) pattern of dried PVP on substrate without fluorosilane treatment, where a coffee ring effect is clearly observed; (c) pattern of the dried PVP on substrate treated with fluorosilane.
JW2A.74.pdf
CLEO:2013 Technical Digest © OSA 2013
(a) (c)) (b) power Figure 2 (a) Micrograph of the multiplexed gas sensor; (b) transmission spectrum (i.e., transmitted power divided by the incident po in the bus waveguide in (a) for different wavelengths) of the gas sensor at TM polarization; (c) Image of the gas sensor sitting on the optical stage covered by a gas flow cell.
The transmission spectrum of the gas sensor is shown in Fig. 2(b). Each resonance is labeled with its corresponding resonator number.. The spacing between two neighboring resonances of resonator #5 is ~ 23 nm, which agrees well with the theoretical calculations of the FSR. The sensor is then integrated with a customized glass chamber and tested with gas analytes. Four volatile organic compounds, isopropanol isopropanol (IPA), methanol, benzene and acetone, were tested with the four selected s polymers. The he response pattern of the four analytes with respect to the four specified polymers is shown in Fig. 3, showing the normalized resonance wavelength drifts when each of the saturated gas analytes is injected. injected This data clearly shows the diversity in the response of the different polymer coatings to the different gas analytes. Further tests with additional polymers and target gas analytes are ongoing and a detailed ed discussion will be covered in the conference.
Figure 3 Normalized response patterns of the four test gas analytes with respect to the four polymers.
References [1] J. T. Robinson, L. Chen, M. Lipson, "On-chip chip gas detection in silicon optical microcavities,” microc Optics Express, 16,, 4296 4296-4301, (2008). [2] N. A. Yebo, P. Lommens, Z. Hens, R. Baets, "An integrated optic ethanol vapor sensor based on a silicon-on-insulator silicon insulator microring resonator coated with a porous ZnO film,"" Optics Express, 18, 11859-11866, (2010). [3] A. Ksendzov, M. L. Homer, A. M. Manfreda,, "Integrated optics ring-resonator ring resonator chemical sensor with polymer transduction layer," Electronics Letters, 40, 63-65, (2004). [4] P. C. Jurs, G. A. BakkenH. E. McClelland,, "Computational methods for the analysis of chemical sensor array data from volatile analytes," analytes Chemical Reviews, 100, 2649-2678, (2000). [5] K. Reddy, Y. B. Guo, J. Liu, W. Lee, M. K. K. Oo, X. D. Fan, “Rapid, sensitive, and multiplexed on-chip on chip optical sensors for micro micro-gas chromatography,” Lab on a Chip, 12, 901-905, (2012 2012) [6] Z. Xia, A. Eftekhar, M. Soltani, B. Momeni, Q. Li, M. Chamanzar, S. Yegananraynana, and A. Adibi, “High resolution on on-chip spectroscopy based on miniaturized microdonut resonators,” Optics Express, 19, 12356-12364, (2011) [7] Z. Xia, A. Eftekhar, Q. Li, and A. Adibi, “On--Chip Chip Multiplexed Photonic Gas Sensing for VOC Detection”, IPC 2012, San Francisco, CA, September 2012. [8] A. Alipour,, E. S. Hosseini, A. A. Eftekhar, B. Momeni, and A. Adibi, "Athermal performance in high-Q high polymer-clad clad silicon microdisk resonators," Optics Letter, 35, 3462-3464,, (2010). [9] D. X. Xu, M. Vachon, A. Densmore, ensmore, R. Ma, S. Janz, A. Delage, J. Lapointe, P. Cheben, J. H. Schmid, E. Post, S. Messaoudene, J. J.-M. Fedeli, "Real-time time cancellation of temperature induced reso resonance shifts in SOI wire waveguide ring resonator label-free free biosensor arrays," Optics Express, 18, 22867-22879, (2010). [10] S. A. Sydlik, Z. Chen, T. M. Swager,, “Triptycene Polyimides: Soluble Polymers with High Thermal Stability and Low Refractive Indices,” Macromolecules, 44, 976-980 (2011).
