dry-film-photoresist-based-electrochemical-microfluidic-biosensor

Dry Film Photoresist-based Electrochemical Microfluidic Biosensor Platform: Device Fabrication, On-chip Assay Preparation, and System Operation

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An ...

University of Freiburg

The aim of this prospective study was to investigate the effects of electrohydraulic extracorporeal shock wave lithotripsy (ESWL) on the transient evoked otoacoustic emissions (TEOAEs) of the patients on whom ESWL was applied for urinary stones.

Effects of extracorporeal shock wave lithotripsy treatment on transient evoked otoacoustic emissions in patients with urinary lithiasis.

We investigated the effect of intranasal packing placed after septoplasty or alternatively suturing the septum without inserting a packing on systemic oxygen saturation and patient comfort.

[The effect of nasal packing and suture technique on systemic oxygen saturation and patient comfort after septoplasty].

We investigated the effect of nasal packing or suturing of the nasal septum after septoplasty on oxidative stress.

[The effect of suturing technique and nasal packing on oxidative stress in septoplasty operations].

Miniaturized diagnostic devices hold the promise of accelerate the specific and sensitive detection of various biomarkers, which can translate into many areas of medicine - from cheaper clinical trials, to early diagnosis and treatment of complex diseases. Therefore, we report on a disposable integrated chip-based capillary immunoassay featuring a microfluidic ELISA format combining electrochemical detection and low-cost fabrication employing a dry film photoresist, Vacrel(®) 8100. The readily accessible carboxylate groups on the material surface allow fast and high yield immobilization of biomolecules using amine-specific coupling via reactive esters requiring no laborious surface pretreatment. The integrated microfluidic system provides a convenient platform for a flow-through immunoassay. Capillary force is used for easy reagent delivery and loading the chip channel. We performed rapid quantification of serum level of substance P, a potential biomarker of acute neuroinflammation, using the developed microfluidic immunochip. Our miniaturized assay demonstrated a sensitive electrochemical detection of the antigen at 15.4pgml(-1) (11.5pM) using only 5µl of the biological fluid while cutting the total assay preparation time in half and the read-out time to 10min. Combining microfluidics and fabrication suitable for mass production with the capability of testing clinically relevant samples creates conditions for the construction of low-cost and portable point of care diagnostic devices with minimal auxiliary electronics.

Sensitive, rapid and quantitative detection of substance P in serum samples using an integrated microfluidic immunochip.

We report a simple, low-cost and lift-off free fabrication approach for periodic structures with adjustable nanometer gaps for interdigitated electrode arrays (IDAs). It combines an initial structure and two deposition process steps; first a dielectric layer is deposited, followed by a metal evaporation. The initial structure can be realized by lithography or any other structuring technique (e.g., nano imprint, hot embossing or injection molding). This method allows the fabrication of nanometer sized gaps and completely eliminates the need for a lift-off process. Different substrate materials like silicon, Pyrex or polymers can be used. The electrode gap is controlled primarily by sputter deposition of the initial structure, and thus, adjustable gaps in the nanometer range can be realized independently of the mask or stamp pattern. Electrochemical characterizations using redox cycling in ferrocenemethanol (FcMeOH) demonstrate signal amplification factors of more than 110 together with collection factors higher than 99%. Furthermore, the correlation between the gap width and the amplification factor was studied to obtain an electrochemical performance assessment of the nano gap electrodes. The results demonstrate an exponential relationship between amplification factor and gap width.

Lift-Off Free Fabrication Approach for Periodic Structures with Tunable Nano Gaps for Interdigitated Electrode Arrays.

The excessive use of antibiotics in human and veterinary medicine causes the emergence of multidrug resistant bacteria. In this context, the surveillance of many different antibiotics provokes a worldwide challenge. Hence, fast and versatile multianalyte single-use biosensors are of increasing interest for many fields such as medical analysis or environmental and food control. Here we present a microfluidic platform enabling the electrochemical readout of up to eight enzyme-linked assays (ELAs), simultaneously. To demonstrate the applicability of this platform for the surveillance and monitoring of antibiotics, we used highly sensitive biomolecular sensor systems for the simultaneous detection of two commonly employed antibiotic classes tetracycline and streptogramin. Thus, microfluidic channel networks are designed, comprising distinct numbers of immobilization sections with a very low volume of 680 nL each. These passively metered sections can be actuated separately for an individual assay procedure. The limits of detection (LOD) are determined, with high precision, to 6.33 and 9.22 ng mL(-1) for tetracycline and pristinamycin, respectively. The employed channel material, dry film photoresist (DFR), allows an easy storage of preimmobilized assays with a shelf life of at least 3 months. Multianalyte measurements in a complex medium are demonstrated by the simultaneous detection of both antibiotics in spiked human plasma within a sample-to-result time of less than 15 min.

Multianalyte Antibiotic Detection on an Electrochemical Microfluidic Platform.

Multiplexed point-of-care testing (xPOCT), which is simultaneous on-site detection of different analytes from a single specimen, has recently gained increasing importance for clinical diagnostics, with emerging applications in resource-limited settings (such as in the developing world, in doctors' offices, or directly at home). Nevertheless, only single-analyte approaches are typically considered as the major paradigm in many reviews of point-of-care testing. Here, we comprehensively review the present diagnostic systems and techniques for xPOCT applications. Different multiplexing technologies (e.g., bead- or array-based systems) are considered along with their detection methods (e.g., electrochemical or optical). We also address the unmet needs and challenges of xPOCT. Finally, we critically summarize the in-field applicability and the future perspectives of the presented approaches.

Can Dincer

Department of Microsystems Engineering,
Freiburg Materials Research Center

University of Freiburg

Dry Film Photoresist-based Electrochemical Microfluidic Biosensor Platform: Device Fabrication, On-chip Assay Preparation, and System Operation

Can Dincer

Department of Microsystems Engineering,Freiburg Materials Research Center

University of Freiburg

Dry Film Photoresist-based Electrochemical Microfluidic Biosensor Platform: Device Fabrication, On-chip Assay Preparation, and System Operation

Department of Microsystems Engineering,
Freiburg Materials Research Center