Lab-on-a-chip or Micro total analysis systems (μTAS) 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 μTAS 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.
The advent of microoptoelectromechanical systems (MOEMS) and its integration with other technologies such as microfluidics, microthermal, immunoproteomics, etc. has led to the concept of an integrated micro-total-analysis systems (µTAS) or Lab-on-a-Chip for chemical and biological applications. Recently, research and development of µTAS have attained a significant growth rate over several biodetection sciences, in situ medical diagnoses, and point-of-care testing applications. However, it is essential to develop suitable biophysical label-free detection methods for the success, reliability, and ease of use of the µTAS. We proposed an infrared (IR)-based evanescence wave detection system on the silicon-on-insulator platform for biodetection with µTAS. The system operates on the principle of bio-optical interaction that occurs due to the evanescence of light from the waveguide device. The feasibility of biodetection has been experimentally investigated by the detection of horse radish peroxidase upon its reaction with hydrogen peroxide
Recent advancements in the integration of photonic technologies with microfluidics for Micro-Total Analysis Systems
(μTAS) have paved way for the realization of a lot of potential applications in the field of biosensing and biomedical
detections. Some of the prominent features of these integrated μTAS are improved performance, high sensitivity and
signal-to-noise ratio, reduced consumption of samples and reagents, and portability, among others. In this work, a hybrid
integrated biophotonic μTAS on silicon-polymer platform is presented. Herein, the optical fibers are directly integrated
with the Silicon microfluidic chip and an Echelle grating based Spectrometer-on-Chip on Silica-on-Silicon (SOS) is
integrated with the opto-microfluidic assembly. Flow actuation within the system is enabled by a mechanical Piezodriven
Valveless Micropump (PVM). Finite Element Analysis (FEA) has been carried out in order to study the behavior
of the fluid flow within the microfluidic channels due to the piezo actuation, and the geometry of the bio-detection
chamber within the microfluidic system has been optimized accordingly in order to obtain no-stagnation flow conditions.
The opto-microfluidic performance and the piezo-actuated valveless micropump were characterized in separate
experiments. The integrated μTAS was tested for flow cytometry and particle detection using laser induced fluorescence.
The experimental results show that the system is suitable for high throughput biodetections.
Bio-security for health monitoring and diagnosis are the needs of the hour, for rapid detection of biological and chemical
species. This calls for a necessity to develop a cost effective miniaturized and portable biosensor device for in-situ
biomedical applications and Point-of-Care Testing (POCT). While portability of the biosensor is required for in-situ
medical detections, miniaturization is essential for handling smaller sample volumes and high throughput. Thus, the
above mentioned concerns cannot be addressed unless a fully integrated biosensor system is developed. In this work, an
integrated opto microfluidic based Lab-on-a-chip device is proposed for carrying out fluorescence based biodetection.
The input and output fibers were integrated with the microfluidic channel so as to make a robust setup. Fluorescence
detection was carried out using Alexafluor 647 tagged antibody particles and the output was measured with a
Spectrometer-on-Chip, integrated with the device. The experimental results prove that the proposed device is highly
suitable for Lab-on-a-Chip applications.
The advent of microfluidics has provided a tremendous boost to the field of health care for the development of practical in-situ medical diagnoses and Point-of-Care (POC) testing methods. Optical microfluidics offers a lot of scope for carrying out successful biodetections through different target detection techniques such as optical absorption, fluorescence, etc. Two main issues in carrying out successful biodetection on microfluidic platform are the problem of biomolecule immobilization onto the surface of the microfluidic channel and efficient mixing of the bio-fluids necessary to achieve proper bio-interaction. In most cases, the biodetection involves two or more biological specimens, such as enzyme-substrate, antigen-antibody, protein-protein etc., and therefore, it is necessary to discover a solution which addresses to the needs of both immobilization and multi-molecular interactions. In this work, a novel technique of flow controlled molecular sorting is presented, wherein, by appropriate design of the microfluidic channel and by careful control of fluid flow in the system, optimal interaction of the specimens can be achieved through biomolecular sorting, thereby overcoming the problem of bio-immobilization onto the surface of the microfluidic channel. Herein, Finite Element Modeling (FEM) of flow behavior within the microfluidic channel has been carried out for different channel geometries, which is essential for the appropriate choice of microfluidic system for the present application. The technique of implementing the immobilization-free multi molecular bio-interactions in the proposed microfluidic system is explained and the feasibility of carrying out optical microfluidics based biodetection is demonstrated.
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.