title: Integrated optical detection of autonomous capillary microfluidic immunoassays:a hand-held point-of-care prototype.
abstract: The miniaturization of biosensors using microfluidics has potential in enabling the development of point-of-care devices, with the added advantages of reduced time and cost of analysis with limits-of-detection comparable to those obtained through traditional laboratory techniques. Interfacing microfluidic devices with the external world can be difficult especially in aspects involving fluid handling and the need for simple sample insertion that avoids special equipment or trained personnel. In this work we present a point-of-care prototype system by integrating capillary microfluidics with a microfabricated photodiode array and electronic instrumentation into a hand-held unit. The capillary microfluidic device is capable of autonomous and sequential fluid flow, including control of the average fluid velocity at any given point of the analysis. To demonstrate the functionality of the prototype, a model chemiluminescence ELISA was performed. The performance of the integrated optical detection in the point-of-care prototype is equal to that obtained with traditional bench-top instrumentation. The photodiode signals were acquired, displayed and processed by a simple graphical user interface using a computer connected to the microcontroller through USB. The prototype performed integrated chemiluminescence ELISA detection in about 15 min with a limit-of-detection of ≈2 nM with an antibody-antigen affinity constant of ≈2×10(7) M(-1).
authors.affiliation: INESC Microsistemas e Nanotecnologias, IN-Institute of Nanoscience and Nanotechnology, Lisbon, Portugal.
authors.forename: P
authors.initials: P
authors.lastname: Novo
authors.affiliation: INESC Microsistemas e Nanotecnologias, IN-Institute of Nanoscience and Nanotechnology, Lisbon, Portugal.
authors.forename: V
authors.initials: V
authors.lastname: Chu
authors.affiliation: INESC Microsistemas e Nanotecnologias, IN-Institute of Nanoscience and Nanotechnology, Lisbon, Portugal; Department of Bioengineering, Instituto Superior Técnico, Lisbon, Portugal. Electronic address: joao.conde@tecnico.ulisboa.pt.
authors.forename: J P
authors.initials: JP
authors.lastname: Conde
mesh_terms: D000818:Animals; D000915:Antibody Affinity; D015374:Biosensing Techniques / Q000295:instrumentation; D004797:Enzyme-Linked Immunosorbent Assay; D004867:Equipment Design; D007118:Immunoassay / Q000295:instrumentation*; D007074:Immunoglobulin G / Q000032:analysis / Q000276:immunology; D057230:Limit of Detection; D008163:Luminescent Measurements / Q000295:instrumentation*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D019095:Point-of-Care Systems; D011817:Rabbits
chemical_list: D007074:Immunoglobulin G
keywords: Autonomous; Capillary microfluidics; ELISA; Photodiodes; Point-of-care