Brain metastasis is one of the main causes of mortality among breast cancer patients, but the ori... more Brain metastasis is one of the main causes of mortality among breast cancer patients, but the origins and the mechanisms that drive this process remain poorly understood. Here, we report that the upregulation of certain CXCR2-associated ligands in the brain metastatic variants of the breast cancer cells (BrM) dynamically activate the corresponding CXCR2 receptors on the neutrophils, thereby resulting in the modulation of certain key functional neutrophil responses towards the BrM. Using established neutrophil-tumor biomimetic co-culture models, we show that the upregulation of CXCR2 increases the recruitment of Tumor-Associated Neutrophils (TANs) towards the BrM, to enable location-favored formation of Neutrophil Extracellular Traps (NETs). Inhibition of CXCR2 using small molecule antagonist AZD5069 reversed this behavior, limiting the neutrophil responses to the BrM and retarding the reciprocal tumor development. We further demonstrate that abrogation of NETs formation using Neutro...
Neutrophils are the most abundant type of leukocytes in the blood, traditionally regarded as the ... more Neutrophils are the most abundant type of leukocytes in the blood, traditionally regarded as the first immune responders to infections and inflammations. In the context of tumors, neutrophils have been shown to possess both tumor-promoting and tumor-limiting properties. A better understanding of the inter-cellular dynamics between the neutrophils and aggregated tumors could possibly shed light on the different modalities of neutrophil involvement in tumor progression. To study in-vitro the interactional dynamics of neutrophils and growing tumor aggregates, in this work, we engineered a novel, microfluidics-integrated, three-dimensional (3D) tumor-immune microenvironment (TIME)-on-Chip device, and we investigated the effect of neutrophils on the inception of collective 3D invasion of ovarian tumor cells. Herein, tumor spheroids generated and cultured on hydrogel based multi-microwell plates, and embedded within collagen matrix of defined thickness, were magnetically hybrid-integrated...
International Journal of Energy Sector Management, 2019
Purpose The purpose of this paper is to answer this question by discussing the practicality of im... more Purpose The purpose of this paper is to answer this question by discussing the practicality of implementing microreactor technology towards large-scale renewable energy generation, as well as provide an incentive for future researchers to utilize microreactors as a useful alternative tool for green energy production. However, can microreactors present a viable solution for the generation of renewable energy to tackle the on-going global energy crisis? Design/methodology/approach In this paper, the practicality of implementing microreactor technology toward large-scale renewable energy generation is discussed. Specific areas of interest that elucidate considerable returns of microreactors toward renewable energy production are biofuel synthesis, hydrogen conversion and solar energy harvesting. Findings It is believed that sustained research on microreactors can significantly accelerate the development of new energy production methods through renewable sources, which will undoubtedly ...
Magnetically anchored microboats that can reliably and rapidly create air–liquid interface cultur... more Magnetically anchored microboats that can reliably and rapidly create air–liquid interface culture conditions in substrate-stiffness tunable epithelial cell cultures.
With recent advances in immunotherapy, it is evident that targeting the tumor microenvironment (T... more With recent advances in immunotherapy, it is evident that targeting the tumor microenvironment (TME) is an effective strategy to treat lung cancer (LC), however, more than half LC patients are still resistant to therapy. Limited attention was given to the relevance of the innate immune system despite its critical role in triggering adaptive responses. Neutrophils (PMNs) are the predominant circulating leukocyte in humans. PMNs are associated with developing lesions and are the main immune component of primary non-small cell LC (NSCLC). Multiple studies support the notion that PMNs promote tumor progression, however, the exact mechanisms in which these PMNs are recruited to the primary and metastatic lung TMEs remain unclear. To this end, we examined available genomic databases of > 1,000 NSCLC primary adenocarcinoma (ADC) patients and observed that high expression of all CXCR2 ligands (CXCL1-8 and MIF) correlate with poor survival in lung ADC. Lung ADC patients display one of the highest fold increases of these ligands as compared to all other cancers. We then performed shRNA knock down (KD) of CXCL1 and MIF in A549 and tested the migration of PMNs towards treated and control cell lines using the novel microfluidic device. We observe 3-fold increase of PMN migration towards A549 compared to control. This increase was significantly inhibited in MIF and CXCL1 KDs as well as using MIF and CXCL1 neutralizing antibodies (NA) as compared to controls. PMN migration was higher to A549 then to PC9EN, and treatment of PMNs with a CXCR2 NA led to a decrease in their migration to A549 while unaffecting their migration to PC9EN. Due to the lack of similar genomic databases on LC metastasis, we profiled liver homogenates of mice intrasplenically injected with liver-metastatic Lewis lung carcinoma (LLC) and observed that Cxcl1 was the most overexpressed gene as compared to non-tumor bearing mice (non-TBM). We then KD CXCL1 from the liver metastatic LLC cell line and compared its capacity to recruit PMNs in live mice using intravital microscopy. We observe a decrease in the number of PMNs around developing CXCL1 KD LLC tumors compared to control LLC. We also observe a decrease in PMN migration toward the CXCL1 KD LLC tumors as compared the control LLC. This resulted in a significant decrease in liver metastasis of the CXCL1 KD LLC as compared to control LLC injected mice. Altogether, our data highlight the importance of CXCR2-mediated PMN migration in primary LC and the establishment of liver metastasis from LC. Thus, inhibiting CXCR2 represents a promising strategy to impede primary tumor growth and metastatic dissemination of LC. Citation Format: Roni F. Rayes, Jack G. Mouhanna, Claire Wang, Simon Milette, Carson Wong, Mariana Usatii, Betty Giannias, France Bourdeau, Rachel Mot, Arvind Chandrasekaran, Christopher Moraes, Sidong Huang, Daniela Quail, Logan Walsh, Veena Sangwan, Nicholas Bertos, Pierre-Olivier Fiset, Jonathan Cools-Lartigue, Lorenzo E. Ferri, Jonathan D. Spicer. Targeting CXCR2-mediated neutrophil recruitment to lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2799.
Neutrophils are associated with developing cancer lesions and are the main immune component of pr... more Neutrophils are associated with developing cancer lesions and are the main immune component of primary non-small cell lung cancer (NSCLC). Multiple studies support the notion that tumor associated neutrophils (TANs) can promote tumor progression. We hypothesize that there is a hierarchy of molecular cues produced by developing lung cancers that guide circulating neutrophils to infiltrate the tumor microenvironment and become TANs. Identifying these cues may permit modulation of neutrophil infiltration within developing lung cancers and may thereby act as an immunotherapeutic tool to suppress cancer progression and improve response to existing therapeutics. To this end, we profiled 5 established NSCLC cell lines representing the common NSCLC subtypes using a qRT-PCR 84 gene panel (A549; KRAS mutant, PC9; EGFR mutant, H1993; MET amplification, H3122; EML4-ALK translocation, HCC78; ROS1 translocation). We focused on 4 of the most commonly upregulated genes in all cell lines, which were...
Innovation in microfluidics-based biological research has been aided by the growing accessibility... more Innovation in microfluidics-based biological research has been aided by the growing accessibility of versatile microscale fabrication techniques, particularly in rapid prototyping of elastomeric polydimethylsiloxane (PDMS) based devices. However, the use of PDMS presents considerable and often unexpected limitations, particularly in interpreting and validating biological data. To rapidly prototype microfluidic culture systems in conventional plastics commonly used in cell culture, we developed 'thermal scribing', a one-step micromachining technique in which thermoplastics are locally patterned by a heated tip, moving in user-controlled patterns. To demonstrate and study the thermal scribing process, we modified an inexpensive desktop hobby craft cutter with a soldering iron to scribe micropatterns on polystyrene substrates. The thermal scribing technique is useful for creating a variety of channel profiles and geometries, which cannot be readily achieved using other microfab...
Medical diagnostics using microsystems have gained a lot of importance in the recent years to dev... more Medical diagnostics using microsystems have gained a lot of importance in the recent years to develop a fully integrated, cost effective and easy-to-use sensor for in-situ detection of biomolecules. In the present work, the feasibility of developing an evanescent wave biosensor on Silicon-On-Insulator (SOI) platform through waveguide based Micro-Electro-Mechanical Systems (MEMS) is studied. Herein, the proposed waveguide system has been modeled through Finite Difference (FD) technique for different evanescent field conditions and the results for modal parameters have been compared with Finite Element Modeling (FEM) simulated through FEMLAB. Scalar Beam Propagation Method (BPM) simulations have been carried out with R-Soft for rectangular and anisotropic waveguides and the results of propagation constants obtained from R-Soft have been compared with the FD method and FEM
Flow rectification in a mechanical valveless micropump that has applications in biological and mi... more Flow rectification in a mechanical valveless micropump that has applications in biological and microrocket propulsion is brought about by pressure drop created across the nozzle/diffuser pair in conjunction with the actuation stroke of the micropump. It has been reported that geometric tuning of the diffuser helps in improving the overall diffuser efficiency. The aim of the present work is to apply the geometry tuning principle over a wide range of flow conditions and to study the usability of this technique for optimized micropump design. Finite element modeling (FEM) of the diffuser behavior with geometry tuning has been carried out for different diffuser configurations and flow conditions, and the results have been validated through selective experimentation.
Innovation in microfluidics-based biological research has been aided by the growing accessibility... more Innovation in microfluidics-based biological research has been aided by the growing accessibility of versatile microscale fabrication techniques, particularly in rapid prototyping of elastomeric polydimethylsiloxane (PDMS) based devices. However, the use of PDMS presents considerable and often unexpected limitations, particularly in interpreting and validating biological data. To rapidly prototype microfluidic culture systems in conventional plastics commonly used in cell culture, we developed 'thermal scribing', a one-step micro-machining technique in which thermoplastics are locally patterned by a heated tip, moving in user-controlled patterns. To demonstrate and study the thermal scribing process, we modified an inexpensive desktop hobby craft cutter with a soldering iron to scribe micropatterns on polystyrene substrates. The thermal scribing technique is useful for creating a variety of channel profiles and geometries, which cannot be readily achieved using other microfabrication approaches. The entire fabrication process, including post-processing operations needed to fabricate devices, can be completed within a few hours without the need for skilled engineering expertise or expensive equipment. We apply this technique to demonstrate that induction of functional neutrophil extracellular traps (NETs) can be significantly enhanced over previous studies, when experiments are conducted in microfluidic channels prototyped in an appropriate material. These results ultimately inform the design of neutrophil culture systems and suggest that the inherent ability of neutrophils to form NETs may have been significantly under-reported.
Photonic Applications in Biosensing and Imaging, 2005
Fiber-optic waveguides based Micro-Opto-Electro-Mechanical Systems (MOEMS) form a significant cla... more Fiber-optic waveguides based Micro-Opto-Electro-Mechanical Systems (MOEMS) form a significant class of biosensors which have notable advantages like light weight, low cost and more importantly, the ability to be integrated with bio-systems. In this work, integrated microfluidic fiber-optic waveguide biosensor is presented. The phenomenon of evanescence is employed for sensing mechanism of the device. Herein, the fiber-optic waveguide is integrated with bulk micromachined fluidic channel across which different chemical and biological samples are passed through. The significant refractive index change due to the presence of biological samples that causes the evanescent field condition in the waveguides leads to optical intensity attenuation of the transmitted light. The study of the modulation in optical intensity is used to detect the properties of the species used in the evanescent region. The intensity modulation of light depends upon the geometry of the waveguide, the length of evanescent field, the optical properties of specimen used for producing evanescence and the changes in the properties by their reaction with other specimen. Therefore, this device is proposed for biosensing applications. The Finite Element Analysis (FEA) has been carried out for wave propagation under the evanescent condition for different parametric variations.
Advanced Biomedical and Clinical Diagnostic Systems VIII, 2010
ABSTRACT Lab-on-a-chip or Micro total analysis systems (muTAS) technologies offer a lot of potent... more ABSTRACT Lab-on-a-chip or Micro total analysis systems (muTAS) technologies offer a lot of potential applications for biosensing and biomedical detections. This paper presents the design, fabrication and characterization of a fully integrated siliconpolymer based biophotonic Micro-Total Analysis System for the real-time detection of enzymes and antigens. This device uses optical detection methods i.e, optical absorption, Laser induced fluorescence and evanescence measurement technique to detect the presence, concentration and the activity of biomolecules. The main components of the proposed system are microfluidic unit and micromechanical fluid actuation system, integrated with the optical detection systems. An Echelle grating based Spectrometer-on-Chip on Silica-on-Silicon (SOS) is integrated with the opto-microfluidic assembly for fluorescence detection. On-Chip fabrication and integration of valveless micropump has been carried out in order to facilitate the transportation of fluid within the system. The important advantages of the proposed muTAS are functional independence of each module of the system, simultaneous multi-analyte detection, rapid, precise and discriminating results, low background/high signal-to-noise ratio, lack of moving parts, robust, portability, and feasibility of bulk fabrication.
ASME 2010 7th International Symposium on Fluid-Structure Interactions, Flow-Sound Interactions, and Flow-Induced Vibration and Noise: Volume 3, Parts A and B, 2010
ABSTRACT In this work, a Piezo actuated Valveless micropump is proposed for applications in Micro... more ABSTRACT In this work, a Piezo actuated Valveless micropump is proposed for applications in Micro-Total Analysis Systems (μTAS) and Lab-on-a-Chip. Flow rectification in the micropump has been brought about with the use of a diffuser element. The device is fabricated on PDMS-Glass substrate with the glass acting as the diaphragm. A PZT disc is integrated with the setup for actuation. The micropump has been characterized for its dynamic behavior, flow characteristics, and pressure. It was found that the maximum flow rate for the micropump was obtained at low frequency which makes it usable for practical μTAS applications.
International Journal of Manufacturing Technology and Management, 2006
ABSTRACT A hybrid micro-machining technique suitable for reducing surface roughness in different ... more ABSTRACT A hybrid micro-machining technique suitable for reducing surface roughness in different optical micro-systems environment is presented. In general, the Micro-Opto-Electro-Mechanical Systems (MOEMS) consist of waveguide-based devices and non-waveguide-based micro-systems. The proposed technique is suitable for both kinds of applications. This paper also presents two types of micro-machining, namely, isotropic gas phase Xenon difluoride (XeF<sub align="right"> 2 ) pulse etching and wet anisotropic etching with Tetra Methyl Ammonium Hydroxide (TMAH), along with the mechanism of hybrid micro-machining. The influence of surface roughness on scattering loss in the two kinds of optical micro-systems has been analysed and the results are presented. The improvement in surface roughness due to the proposed technique is demonstrated by experimental characterisation of the roughness parameters using a Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM). The results indicate a clear improvement in surface roughness and the induced scattering loss due to the proposed hybrid micro-machining technique.
Brain metastasis is one of the main causes of mortality among breast cancer patients, but the ori... more Brain metastasis is one of the main causes of mortality among breast cancer patients, but the origins and the mechanisms that drive this process remain poorly understood. Here, we report that the upregulation of certain CXCR2-associated ligands in the brain metastatic variants of the breast cancer cells (BrM) dynamically activate the corresponding CXCR2 receptors on the neutrophils, thereby resulting in the modulation of certain key functional neutrophil responses towards the BrM. Using established neutrophil-tumor biomimetic co-culture models, we show that the upregulation of CXCR2 increases the recruitment of Tumor-Associated Neutrophils (TANs) towards the BrM, to enable location-favored formation of Neutrophil Extracellular Traps (NETs). Inhibition of CXCR2 using small molecule antagonist AZD5069 reversed this behavior, limiting the neutrophil responses to the BrM and retarding the reciprocal tumor development. We further demonstrate that abrogation of NETs formation using Neutro...
Neutrophils are the most abundant type of leukocytes in the blood, traditionally regarded as the ... more Neutrophils are the most abundant type of leukocytes in the blood, traditionally regarded as the first immune responders to infections and inflammations. In the context of tumors, neutrophils have been shown to possess both tumor-promoting and tumor-limiting properties. A better understanding of the inter-cellular dynamics between the neutrophils and aggregated tumors could possibly shed light on the different modalities of neutrophil involvement in tumor progression. To study in-vitro the interactional dynamics of neutrophils and growing tumor aggregates, in this work, we engineered a novel, microfluidics-integrated, three-dimensional (3D) tumor-immune microenvironment (TIME)-on-Chip device, and we investigated the effect of neutrophils on the inception of collective 3D invasion of ovarian tumor cells. Herein, tumor spheroids generated and cultured on hydrogel based multi-microwell plates, and embedded within collagen matrix of defined thickness, were magnetically hybrid-integrated...
International Journal of Energy Sector Management, 2019
Purpose The purpose of this paper is to answer this question by discussing the practicality of im... more Purpose The purpose of this paper is to answer this question by discussing the practicality of implementing microreactor technology towards large-scale renewable energy generation, as well as provide an incentive for future researchers to utilize microreactors as a useful alternative tool for green energy production. However, can microreactors present a viable solution for the generation of renewable energy to tackle the on-going global energy crisis? Design/methodology/approach In this paper, the practicality of implementing microreactor technology toward large-scale renewable energy generation is discussed. Specific areas of interest that elucidate considerable returns of microreactors toward renewable energy production are biofuel synthesis, hydrogen conversion and solar energy harvesting. Findings It is believed that sustained research on microreactors can significantly accelerate the development of new energy production methods through renewable sources, which will undoubtedly ...
Magnetically anchored microboats that can reliably and rapidly create air–liquid interface cultur... more Magnetically anchored microboats that can reliably and rapidly create air–liquid interface culture conditions in substrate-stiffness tunable epithelial cell cultures.
With recent advances in immunotherapy, it is evident that targeting the tumor microenvironment (T... more With recent advances in immunotherapy, it is evident that targeting the tumor microenvironment (TME) is an effective strategy to treat lung cancer (LC), however, more than half LC patients are still resistant to therapy. Limited attention was given to the relevance of the innate immune system despite its critical role in triggering adaptive responses. Neutrophils (PMNs) are the predominant circulating leukocyte in humans. PMNs are associated with developing lesions and are the main immune component of primary non-small cell LC (NSCLC). Multiple studies support the notion that PMNs promote tumor progression, however, the exact mechanisms in which these PMNs are recruited to the primary and metastatic lung TMEs remain unclear. To this end, we examined available genomic databases of > 1,000 NSCLC primary adenocarcinoma (ADC) patients and observed that high expression of all CXCR2 ligands (CXCL1-8 and MIF) correlate with poor survival in lung ADC. Lung ADC patients display one of the highest fold increases of these ligands as compared to all other cancers. We then performed shRNA knock down (KD) of CXCL1 and MIF in A549 and tested the migration of PMNs towards treated and control cell lines using the novel microfluidic device. We observe 3-fold increase of PMN migration towards A549 compared to control. This increase was significantly inhibited in MIF and CXCL1 KDs as well as using MIF and CXCL1 neutralizing antibodies (NA) as compared to controls. PMN migration was higher to A549 then to PC9EN, and treatment of PMNs with a CXCR2 NA led to a decrease in their migration to A549 while unaffecting their migration to PC9EN. Due to the lack of similar genomic databases on LC metastasis, we profiled liver homogenates of mice intrasplenically injected with liver-metastatic Lewis lung carcinoma (LLC) and observed that Cxcl1 was the most overexpressed gene as compared to non-tumor bearing mice (non-TBM). We then KD CXCL1 from the liver metastatic LLC cell line and compared its capacity to recruit PMNs in live mice using intravital microscopy. We observe a decrease in the number of PMNs around developing CXCL1 KD LLC tumors compared to control LLC. We also observe a decrease in PMN migration toward the CXCL1 KD LLC tumors as compared the control LLC. This resulted in a significant decrease in liver metastasis of the CXCL1 KD LLC as compared to control LLC injected mice. Altogether, our data highlight the importance of CXCR2-mediated PMN migration in primary LC and the establishment of liver metastasis from LC. Thus, inhibiting CXCR2 represents a promising strategy to impede primary tumor growth and metastatic dissemination of LC. Citation Format: Roni F. Rayes, Jack G. Mouhanna, Claire Wang, Simon Milette, Carson Wong, Mariana Usatii, Betty Giannias, France Bourdeau, Rachel Mot, Arvind Chandrasekaran, Christopher Moraes, Sidong Huang, Daniela Quail, Logan Walsh, Veena Sangwan, Nicholas Bertos, Pierre-Olivier Fiset, Jonathan Cools-Lartigue, Lorenzo E. Ferri, Jonathan D. Spicer. Targeting CXCR2-mediated neutrophil recruitment to lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2799.
Neutrophils are associated with developing cancer lesions and are the main immune component of pr... more Neutrophils are associated with developing cancer lesions and are the main immune component of primary non-small cell lung cancer (NSCLC). Multiple studies support the notion that tumor associated neutrophils (TANs) can promote tumor progression. We hypothesize that there is a hierarchy of molecular cues produced by developing lung cancers that guide circulating neutrophils to infiltrate the tumor microenvironment and become TANs. Identifying these cues may permit modulation of neutrophil infiltration within developing lung cancers and may thereby act as an immunotherapeutic tool to suppress cancer progression and improve response to existing therapeutics. To this end, we profiled 5 established NSCLC cell lines representing the common NSCLC subtypes using a qRT-PCR 84 gene panel (A549; KRAS mutant, PC9; EGFR mutant, H1993; MET amplification, H3122; EML4-ALK translocation, HCC78; ROS1 translocation). We focused on 4 of the most commonly upregulated genes in all cell lines, which were...
Innovation in microfluidics-based biological research has been aided by the growing accessibility... more Innovation in microfluidics-based biological research has been aided by the growing accessibility of versatile microscale fabrication techniques, particularly in rapid prototyping of elastomeric polydimethylsiloxane (PDMS) based devices. However, the use of PDMS presents considerable and often unexpected limitations, particularly in interpreting and validating biological data. To rapidly prototype microfluidic culture systems in conventional plastics commonly used in cell culture, we developed 'thermal scribing', a one-step micromachining technique in which thermoplastics are locally patterned by a heated tip, moving in user-controlled patterns. To demonstrate and study the thermal scribing process, we modified an inexpensive desktop hobby craft cutter with a soldering iron to scribe micropatterns on polystyrene substrates. The thermal scribing technique is useful for creating a variety of channel profiles and geometries, which cannot be readily achieved using other microfab...
Medical diagnostics using microsystems have gained a lot of importance in the recent years to dev... more Medical diagnostics using microsystems have gained a lot of importance in the recent years to develop a fully integrated, cost effective and easy-to-use sensor for in-situ detection of biomolecules. In the present work, the feasibility of developing an evanescent wave biosensor on Silicon-On-Insulator (SOI) platform through waveguide based Micro-Electro-Mechanical Systems (MEMS) is studied. Herein, the proposed waveguide system has been modeled through Finite Difference (FD) technique for different evanescent field conditions and the results for modal parameters have been compared with Finite Element Modeling (FEM) simulated through FEMLAB. Scalar Beam Propagation Method (BPM) simulations have been carried out with R-Soft for rectangular and anisotropic waveguides and the results of propagation constants obtained from R-Soft have been compared with the FD method and FEM
Flow rectification in a mechanical valveless micropump that has applications in biological and mi... more Flow rectification in a mechanical valveless micropump that has applications in biological and microrocket propulsion is brought about by pressure drop created across the nozzle/diffuser pair in conjunction with the actuation stroke of the micropump. It has been reported that geometric tuning of the diffuser helps in improving the overall diffuser efficiency. The aim of the present work is to apply the geometry tuning principle over a wide range of flow conditions and to study the usability of this technique for optimized micropump design. Finite element modeling (FEM) of the diffuser behavior with geometry tuning has been carried out for different diffuser configurations and flow conditions, and the results have been validated through selective experimentation.
Innovation in microfluidics-based biological research has been aided by the growing accessibility... more Innovation in microfluidics-based biological research has been aided by the growing accessibility of versatile microscale fabrication techniques, particularly in rapid prototyping of elastomeric polydimethylsiloxane (PDMS) based devices. However, the use of PDMS presents considerable and often unexpected limitations, particularly in interpreting and validating biological data. To rapidly prototype microfluidic culture systems in conventional plastics commonly used in cell culture, we developed 'thermal scribing', a one-step micro-machining technique in which thermoplastics are locally patterned by a heated tip, moving in user-controlled patterns. To demonstrate and study the thermal scribing process, we modified an inexpensive desktop hobby craft cutter with a soldering iron to scribe micropatterns on polystyrene substrates. The thermal scribing technique is useful for creating a variety of channel profiles and geometries, which cannot be readily achieved using other microfabrication approaches. The entire fabrication process, including post-processing operations needed to fabricate devices, can be completed within a few hours without the need for skilled engineering expertise or expensive equipment. We apply this technique to demonstrate that induction of functional neutrophil extracellular traps (NETs) can be significantly enhanced over previous studies, when experiments are conducted in microfluidic channels prototyped in an appropriate material. These results ultimately inform the design of neutrophil culture systems and suggest that the inherent ability of neutrophils to form NETs may have been significantly under-reported.
Photonic Applications in Biosensing and Imaging, 2005
Fiber-optic waveguides based Micro-Opto-Electro-Mechanical Systems (MOEMS) form a significant cla... more Fiber-optic waveguides based Micro-Opto-Electro-Mechanical Systems (MOEMS) form a significant class of biosensors which have notable advantages like light weight, low cost and more importantly, the ability to be integrated with bio-systems. In this work, integrated microfluidic fiber-optic waveguide biosensor is presented. The phenomenon of evanescence is employed for sensing mechanism of the device. Herein, the fiber-optic waveguide is integrated with bulk micromachined fluidic channel across which different chemical and biological samples are passed through. The significant refractive index change due to the presence of biological samples that causes the evanescent field condition in the waveguides leads to optical intensity attenuation of the transmitted light. The study of the modulation in optical intensity is used to detect the properties of the species used in the evanescent region. The intensity modulation of light depends upon the geometry of the waveguide, the length of evanescent field, the optical properties of specimen used for producing evanescence and the changes in the properties by their reaction with other specimen. Therefore, this device is proposed for biosensing applications. The Finite Element Analysis (FEA) has been carried out for wave propagation under the evanescent condition for different parametric variations.
Advanced Biomedical and Clinical Diagnostic Systems VIII, 2010
ABSTRACT Lab-on-a-chip or Micro total analysis systems (muTAS) technologies offer a lot of potent... more ABSTRACT Lab-on-a-chip or Micro total analysis systems (muTAS) technologies offer a lot of potential applications for biosensing and biomedical detections. This paper presents the design, fabrication and characterization of a fully integrated siliconpolymer based biophotonic Micro-Total Analysis System for the real-time detection of enzymes and antigens. This device uses optical detection methods i.e, optical absorption, Laser induced fluorescence and evanescence measurement technique to detect the presence, concentration and the activity of biomolecules. The main components of the proposed system are microfluidic unit and micromechanical fluid actuation system, integrated with the optical detection systems. An Echelle grating based Spectrometer-on-Chip on Silica-on-Silicon (SOS) is integrated with the opto-microfluidic assembly for fluorescence detection. On-Chip fabrication and integration of valveless micropump has been carried out in order to facilitate the transportation of fluid within the system. The important advantages of the proposed muTAS are functional independence of each module of the system, simultaneous multi-analyte detection, rapid, precise and discriminating results, low background/high signal-to-noise ratio, lack of moving parts, robust, portability, and feasibility of bulk fabrication.
ASME 2010 7th International Symposium on Fluid-Structure Interactions, Flow-Sound Interactions, and Flow-Induced Vibration and Noise: Volume 3, Parts A and B, 2010
ABSTRACT In this work, a Piezo actuated Valveless micropump is proposed for applications in Micro... more ABSTRACT In this work, a Piezo actuated Valveless micropump is proposed for applications in Micro-Total Analysis Systems (μTAS) and Lab-on-a-Chip. Flow rectification in the micropump has been brought about with the use of a diffuser element. The device is fabricated on PDMS-Glass substrate with the glass acting as the diaphragm. A PZT disc is integrated with the setup for actuation. The micropump has been characterized for its dynamic behavior, flow characteristics, and pressure. It was found that the maximum flow rate for the micropump was obtained at low frequency which makes it usable for practical μTAS applications.
International Journal of Manufacturing Technology and Management, 2006
ABSTRACT A hybrid micro-machining technique suitable for reducing surface roughness in different ... more ABSTRACT A hybrid micro-machining technique suitable for reducing surface roughness in different optical micro-systems environment is presented. In general, the Micro-Opto-Electro-Mechanical Systems (MOEMS) consist of waveguide-based devices and non-waveguide-based micro-systems. The proposed technique is suitable for both kinds of applications. This paper also presents two types of micro-machining, namely, isotropic gas phase Xenon difluoride (XeF<sub align="right"> 2 ) pulse etching and wet anisotropic etching with Tetra Methyl Ammonium Hydroxide (TMAH), along with the mechanism of hybrid micro-machining. The influence of surface roughness on scattering loss in the two kinds of optical micro-systems has been analysed and the results are presented. The improvement in surface roughness due to the proposed technique is demonstrated by experimental characterisation of the roughness parameters using a Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM). The results indicate a clear improvement in surface roughness and the induced scattering loss due to the proposed hybrid micro-machining technique.
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Papers by Arvind Chandrasekaran