Browsing by Author "Kalantarifard, A."

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Open Access
Label-free sensing in microdroplet-based microfluidic systems
(MDPI Multidisciplinary Digital Publishing Institute, 2018) Kalantarifard, A.; Saateh, A.; Elbuken, Çağlar
Droplet microfluidic systems have evolved as fluidic platforms that use much less sample volume and provide high throughput for biochemical analysis compared to conventional microfluidic devices. The variety of droplet fluidic applications triggered several detection techniques to be applied for analysis of droplets. In this review, we focus on label-free droplet detection techniques that were adapted to various droplet microfluidic platforms. We provide a classification of most commonly used droplet platform technologies. Then we discuss the examples of various label-free droplet detection schemes implemented for these platforms. While providing the research landscape for label-free droplet detection methods, we aim to highlight the strengths and shortcomings of each droplet platform so that a more targeted approach can be taken by researchers when selecting a droplet platform and a detection scheme for any given application.
Open Access
Optical trapping of microparticles and yeast cells at ultra-low intensity by intracavity nonlinear feedback forces
(SPIE, 2020) Kalantarifard, A.; Elahi, P.; Makey, Ghaith; Ünlü, B.; Marago, O. M.; İlday, Fatih Ömer; Volpe, G.; Dholakia, K.; Spalding, G. C.
In standard optical tweezers optical forces arise from the interaction of a tightly focused laser beam with a microscopic particle. The particle is always outside the laser cavity and the incoming beam is not affected by the particle position. Here we describe an optical trapping scheme inside the cavity of a fiber laser where the laser operation is nonlinearly influenced by the displacement of trapped particle and there is a coupling between laser operation to the motion of the trapped particle and this can dramatically enhances optical tweezers action and gives rise to nonlinear feedback forces. This scheme operates using an aspheric lens at low numerical aperture (NA=0.125), NIR wavelength (λ = 1030 nm), and very low average power which results in about two orders of magnitude reduction in exposure to laser intensity compared to standard optical tweezers. Ultra-low intensity at our wavelength can grant a safe, temperature-controlled environment, away from surfaces for microfuidics manipulation of biosamples that are sensitive to light intensity. As the main advantage of our approach and highly relevant application, we observed that we can trap single yeast cells at a very low power, corresponding to an intensity of 0.036 mW μm-2, that is more than a tenfold less intensity than standard techniques reported in the literature.