Aniruddha Puntambekar

Disposable smart lab on a chip for point-of-care clinical diagnostics

This paper presents the development of a disposable plastic biochip incorporating smart passive microfluidics with embedded on-chip power sources and integrated biosensor array for applications in clinical diagnostics and point-of-care testing. The fully integrated disposable biochip is capable of precise volume control with smart microfluidic manipulation without costly on-chip microfluidic components. The biochip has a unique power source using on-chip pressurized air reservoirs, for microfluidic manipulation, avoiding the need for complex microfluidic pumps. In addition, the disposable plastic biochip has successfully been tested for the measurements of partial oxygen concentration, glucose, and lactate level in human blood using an integrated biosensor array. This paper presents details of the smart passive microfluidic system, the on-chip power source, and the biosensor array together with a detailed discussion of the plastic micromachining techniques used for chip fabrication. A handheld analyzer capable of multiparameter detection of clinically relevant parameters has also been developed to detect the signals from the cartridge type disposable biochip. The handheld analyzer developed in this work is currently the smallest analyzer capable of multiparameter detection for point-of-care testing.

Self-aligning microfluidic interconnects for glass- and plastic-based microfluidic systems

In this work, we present novel self-aligning fluidic interconnection techniques with low dead volume and pressure drop for generic microfluidic systems and capillary electrophoresis chips. We have successfully designed, fabricated and characterized two self-aligning fluidic interconnection techniques in this work, both resulting in low dead volume and low pressure drop across the interconnects. The first technique is a serial assembly technique, in which each fluidic interconnect is assembled individually, exhibiting a pressure drop of 977 Pa (0.14 psi) at a flow rate of 100 µl min-1. The second technique is a parallel assembly technique that is suitable for high-density interconnects with multi-stacked generic microfluidic systems, which has a pressure drop of 1024 Pa (0.15 psi) at a flow rate of 100 µl min-1. Furthermore, the parallel assembly technique is ideally suited for plastic-based microfluidic systems. We have simulated the flow characteristics of these interconnection schemes and, based in part on the simulation results, we have designed the above interconnection schemes. We have also characterized these interconnects in terms of the physical robustness of the interconnection scheme. The serial interconnection scheme can theoretically withstand 2.6 MPa and the parallel interconnection scheme can withstand a theoretical maximum pressure of 6.6 MPa.

A novel microfluidic microplate as the next generation assay platform for enzyme linked immunoassays (ELISA)

In this work we introduce a novel microfluidic enzyme linked immunoassays (ELISA) microplate as the next generation assay platform for unparalleled assay performances. A combination of microfluidic technology with standard SBS-configured 96-well microplate architecture, in the form of microfluidic microplate technology, allows for the improvement of ELISA workflows, conservation of samples and reagents, improved reaction kinetics, and the ability to improve the sensitivity of the assay by multiple analyte loading. This paper presents the design and characterization of the microfluidic microplate, and its application in ELISA.

A Plastic Micro Injection Molding Technique Using Replaceable Mold-Disks for Disposable Microfluidic Systems and Biochips

This paper presents an innovative plastic micro injection molding technique using replaceable disk-mold for applications to microfluidic systems and biochips. Precisely patterned and microfabricated wafer-type mold inserts can be easily loaded into the injection molding machine. Processing time for one chip was as fast as 10 seconds while hot embossing techniques require at least several minutes. Less than a few urn of precise patterns were also achieved. A promising new material has also been introduced and characterized using the developed injection molding technique as well as demonstrated for a disposable biochip.

Fixed-volume metering microdispenser module

In this work, we present a novel fixed-volume metering microdispenser module using the sPROMs (structurally programmable microfluidic systems) technology. We have designed, simulated, fabricated and characterized an array of microdispensers with volumes ranging from 50 nL [nanoliter] to 150 nL. We have characterized several key components of the microdispenser, such as passive microvalves and the air-driven liquid column splitting process, using extensive simulations. The fabricated devices show extremely good accuracy (99.2%) and repeatability characteristics. We also present a simple technique for unloading the sub-microL [microliter] volumes from the microfluidic chip for measurement purposes. The dispensers realized in this work have immediate applications as a key ingredient of the lab-on-a-chip device.

A disposable plastic biochip cartridge with on-chip power sources for blood analysis

This paper presents the development of a disposable plastic biochip with embedded on-chip power sources and integrated biosensor array for applications in clinical diagnostics and point-of-care systems. A cartridge type disposable plastic biochip has been successfully developed and demonstrated for precise sample volume control with smart microfluidic manipulation without costly on-chip active microfluidic components. In addition, the disposable plastic biochip has successfully been tested for the measurements of partial oxygen concentration, glucose, and lactate level in human blood using an integrated biosensor array.

Effect of Surface Modification on Thermoplastic Fusion Bonding for 3-D Microfluidics

In this work we have characterized the effect of surface modification, using plasma treatment, on the bond strength of thermoplastic fusion bonding. We have investigated the effect of hydrophilic and hydrophobic surface treatments, for COC (cyclic olefin copolymers), on the bond strength and we show that the hydrophilic surface treatment increases the bond strength whereas; hydrophobic surface treatment significantly lowers the bond strength. The results of this work are of immediate relevance to plastic micromachining techniques for biochip applications and point-of-care systems.

Self-Aligning Microfluidic Interconnects with Low Dead Volume

In this paper, we present a novel self-aligning fluidic interconnection technique with low dead volume and pressure drop for generic microfluidic systems and CE chips. We have successfully designed, fabricated and characterized two self-aligning fluidic interconnection techniques in this work, both resulting in low dead volume and low pressure drop across the interconnects. The first technique is a serial assembly technique, in which each fluidic interconnect is assembled individually, exhibiting a pressure drop of 0.14 psi at a flow rate of 100 μl/min. The second technique is a parallel assembly technique that is suitable for high density interconnects with multi-stacked generic microfluidic systems, which has a pressure drop of 0.15 psi at a flow rate of 100 μl/min. We have also characterized these interconnects in terms of physical robustness of the interconnection scheme.

A New Fixed-Volume Metering Microdispenser Module based on sPROMs Technology

In this work, we present a novel fixed-volume metering microdispenser module using sPROMs (structurally programmable microfluidic system) technology. Several different passive microvalves have been designed and simulated as a key fluidic component for microdispenser modules. With the passive microvalves, new dispenser modules with fixed volume of 50, 100 and 150 nL have been designed, fabricated and then successfully characterized with a precision of less than 0.25 %. We have successfully realized a novel fixed-volume microdispenser in this work.

Novel Biomarkers Detection and Identification by Microfluidic- Based MicroELISA

Miniaturized, high throughput detection technologies including microfluidics systems represent powerful tools for biomarker discovery and analysis. Optimiser™ microplate technology combines microfluidics technology with standard SBS-configured 96-well microplate architecture and allows for the improvement of ELISA workflows. In this review, we present the “standard” and “high sensitivity” capabilities of the Optimiser™ ELISA in detecting human cytokine biomarker; IL-4, resulting in improving sensitivity by 1000-fold higher than the typical conventional ELISA. The Optimiser™ ELISA microplate employs standard ELISA equipment and protocols, selectively reduces sample volume 10-20 fold (Static Mode) and has the capability to amplify assay sensitivity by 1,000 fold (Repetitive Loading Flow-Through Mode) relative to conventional high sensitivity ELISA approaches. Optimiser™ allows sensitive and quantitative detection of biomarkers with demonstrated reproducibility, speed and linearity. In this study we demonstrate the utilization of OptmiserTM in the amplification of low-concentration markers. Optimiser™ microfluidic-based technology represents a revolutionary advancement in ELISA technology, and holds great promise for accurate, sensitive detection of novel biomarkers and its potential applications in clinical diagnosis.