Integration of digital microfluidics with whispering-gallery mode sensors for label-free detection of biomolecules

Wondimu, S. F.; Ecken, Sebastian von der; Ahrens, Ralf; Freude, W.; Guber, A.E.; Koos, C.

doi:10.1039/c6lc01556e

Cited by 31 publications

(19 citation statements)

References 37 publications

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“…However, it was shown that the closed (or two-plate) DMF platforms are capable of performing more versatile operations on droplets (such as moving, splitting and merging) compared to open DMF platforms, especially in EWOD-based DMF 7 . The closed EWOD-based DMF platforms were also successfully employed in isolation of bio-entities such as proteins and cells 8 – 10 . In these systems, bio-entities are generally encapsulated in droplets sandwiched between top and bottom plates containing microwells and electrodes, respectively.…”

Section: Introductionmentioning

confidence: 99%

A magnet-actuated biomimetic device for isolating biological entities in microwells

Sharma

John

Gaddam

et al. 2018

Sci Rep

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Microwell platforms show great promise in single-cell studies and protein measurements because of their low volume sampling, rapid analysis and high throughput screening ability. However, the existing actuation mechanisms to manipulate the target samples and fabrication procedures involved in the microwell-based microfluidic devices are complex, resource-intensive and require an external power source. In this work, we present proof of concept of a simple, power-free and low-cost closed magnet digital microfluidics device for isolating biological entities in femtoliter-sized microwells. The target biological entities were encapsulated in magnetic liquid marbles and shuttled back and forth between micropatterned top and bottom plates in the microdevice to obtain high loading efficiency and short processing time. The microdevice performance was studied through fluorescent detection of three different entities: microbeads, bovine serum albumin (BSA) and Escherichia coli, captured in the microwell array. Almost 80% of the microwells were loaded with single microbeads in five shuttling cycles, in less than a minute. Further, a low volume of BSA was compartmentalized in the microwell array over a two order range of concentration. The microdevice exhibits two unique features: lotus leaf stamps were used to fabricate micropatterns (microwells and micropillars) on top and bottom plates to impart functionality and cost-effectiveness, and the target samples were actuated by a permanent magnet to make the microdevice power-free and simple in operation. The developed biomimetic microdevice is therefore capable of capturing a multitude of biological entities in low-resource settings.

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Section: Introductionmentioning

confidence: 99%

A magnet-actuated biomimetic device for isolating biological entities in microwells

Sharma

John

Gaddam

et al. 2018

Sci Rep

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“…Further improvements are possible by optimizing the functionalization protocol to achieve higher density of receptor molecules, or by optimizing resonator dimensions to increase the overlap of the resonance modes with the surrounding [4]. Furthermore, active analyte agitation during measurements can accelerate response times, for example by using digital microfluidics or continuous flow systems [41][42][43]. In the future, the concept of localized dispensing may be extended to selective functionalization of resonators within a large-scale array to enable simultaneous detection of multiple target molecules.…”

Section: Discussionmentioning

confidence: 99%

Robust label-free biosensing using microdisk laser arrays with on-chip references

Wondimu

Hippler

Hussal³

et al. 2018

Opt. Express

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Whispering-gallery mode (WGM) microdisk lasers show great potential for highly sensitive label-free detection in large-scale sensor arrays. However, when used in practical applications under normal ambient conditions, these devices suffer from temperature fluctuations and photobleaching. Here we demonstrate that these challenges can be overcome by a novel referencing scheme that allows for simultaneous compensation of temperature drift and photobleaching. The technique relies on reference structures protected by locally dispensed passivation materials, and can be scaled to extended arrays of hundreds of devices. We prove the viability of the concept in a series of experiments, demonstrating robust and sensitive label-free detection over a wide range of constant or continuously varying temperatures. To the best of our knowledge, these measurements represent the first demonstration of biosensing in active WGM devices with simultaneous compensation of both photobleaching and temperature drift.

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“…In 2017, Wondimu et al developed WGM optical microcavity‐based label‐free biosensing incorporated in a digital microfluidic system with demonstrated streptavidin detection. [ 198 ] However, the cavities are not silicon‐based but made of polymethyl methacrylate (PMMA), which require bulky instruments (i.e., a high‐power pump laser and spectrometer) and optical focusing with free‐space optical components for measurements.…”

Section: Laboratory Prototypes Toward Poc Applicationsmentioning

confidence: 99%

Silicon‐Based Integrated Label‐Free Optofluidic Biosensors: Latest Advances and Roadmap

Wang

Sánchez

Yin

et al. 2020

Adv Materials Technologies

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By virtue of the well‐developed micro‐ and nanofabrication technologies and rapidly progressing surface functionalization strategies, silicon‐based devices have been widely recognized as a highly promising platform for the next‐generation lab‐on‐a‐chip bioanalytical systems with a great potential for point‐of‐care medical diagnostics. Herein, an overview of the latest advances in silicon‐based integrated optofluidic label‐free biosensing technologies relying on the efficient interactions between the evanescent light field at the functionalized surface and specifically bound analytes is presented. State‐of‐the‐art technologies demonstrating label‐free evanescent wave‐based biomarker detection mainly encompass three device configurations, including on‐chip waveguide‐based interferometers, microring resonators, and photonic‐crystal‐based cavities. Moreover, up‐to‐date strategies for elevating the sensitivities and also simplifying the sensing processes are discussed. Emerging laboratory prototypes with advanced integration and packaging schemes incorporating automatic microfluidic components or on‐chip optoelectronic devices lead to one significant step forward in real applications of decentralized diagnostics. Besides, particular attention is paid to currently commercialized label‐free optical bioanalytical models on the market. Finally, the prospects are elaborated with several research routes toward chip‐scale, low‐cost, highly sensitive, multi‐functional, and user‐friendly bioanalytical systems benefiting to global healthcare.

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Integration of digital microfluidics with whispering-gallery mode sensors for label-free detection of biomolecules

Cited by 31 publications

References 37 publications

A magnet-actuated biomimetic device for isolating biological entities in microwells

A magnet-actuated biomimetic device for isolating biological entities in microwells

Robust label-free biosensing using microdisk laser arrays with on-chip references

Silicon‐Based Integrated Label‐Free Optofluidic Biosensors: Latest Advances and Roadmap

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