Filiz Yesilkoy

University of Wisconsin–Madison | UW · Department of Biomedical Engineering

Biosensors are indispensable tools for public, global, and personalized healthcare as they provide tests that can be used from early disease detection and treatment monitoring to preventing pandemics. We introduce single-wavelength imaging biosensors capable of reconstructing spectral shift information induced by biomarkers dynamically using an adv...

We present optofluidic label-free biosensors leveraging high quality-factor resonances emanated from bound-states-in-the-continuum and novel data processing. The sensors are based on imaging and offer solutions to remove sophisticated spectroscopy instrumentations towards point-of-care applications.

In article number 1906108, Anna Fàbrega, Hatice Altug, and co‐workers present a portable optical biosensor based on nanoparticle‐enhanced digital plasmonic imaging to assist sepsis diagnosis, enabling rapid and sensitive detection of blood‐circulating disease biomarkers. The low‐cost device is tested with patient samples in a hospital and is shown...

Sepsis is a critical health threat, and its survival strictly depends on early diagnosis. A novel portable biosensor based on nanoparticle-enhanced digital plasmonic imaging is reported for rapid and sensitive detection of two sepsis-related biomarkers, procalcitonin and C-reactive protein directly from blood senrm.

New point‐of‐care diagnostic devices are urgently needed for rapid and accurate diagnosis, particularly in the management of life‐threatening infections and sepsis, where immediate treatment is key. Sepsis is a critical condition caused by systemic response to infection, with chances of survival drastically decreasing every hour. A novel portable b...

The manipulation of light via nanoengineered surfaces has excited the optical community in the past few decades. Among the many applications enabled by nanophotonic devices, sensing has stood out due to their capability of identifying miniscule refractive index changes. In particular, when free-space propagating light effectively couples into subwa...

Metasurfaces based on resonant subwavelength photonic structures enable novel ways of wavefront control and light focusing, underpinning a new generation of flat-optics devices¹. Recently emerged all-dielectric asymmetric metasurfaces, composed of arrays of metaunits with broken in-plane inversion symmetry2–7, exhibit high-quality resonances origin...

Sepsis is a condition characterized by a severe stage of blood-infection often leading to tissue damage, organ failure and finally death. Fast diagnosis and identification of the sepsis stage (sepsis, severe sepsis or septic shock) is critical for the patient's evolution and could help in defining the most adequate treatment in order to reduce its...

Modern devices require the tuning of the size, shape and spatial arrangement of nano-objects and their assemblies with nanometre-scale precision, over large-area and sometimes soft substrates. Such stringent requirements are beyond the reach of conventional lithographic techniques or self-assembly approaches. Here, we show nanoscale control over th...

In the version of this Article originally published, the volume, article number and year of ref. 32 were incorrect; they should have read 31, 1802348 (2019). This has now been corrected.

In an effort to address the requirements of next-generation healthcare systems, including personalized medicine, point-of-care diagnostics, and global health surveillance, I will introduce imaging-based portable nanoplasmonic biosensors integrated with microfluidic systems for various bioanalytical applications.

We present a nanophotonic method capable of detecting mid-infrared molecular fingerprints without the need for spectrometry, frequency scanning, or moving mechanical parts. We leverage dielectric metasurfaces featuring ultra-sharp resonances each tuned to discrete frequencies, enabling us to sample molecular absorption signatures over the mid-IR sp...

Mobile and affordable biosensors enabling detection of disease biomarkers from small sample volumes are essential for next-generation healthcare systems. Here, I will introduce ultrasensitive compact biosensors and label-free large-area biomolecule imagers based on nanophotonic metasurfaces.

We present an ultra-sensitive label-free point-of-care platform for potential early diagnosis of sepsis based on lens-free interferometric phase imaging and localized surface plasmon resonance.

Existing clinical methods for bacteria detection lack in speed, sensitivity and importantly in Point-of-Care (PoC) applicability. Thus, finding ways to push the sensitivity of clinical PoC biosensing technologies is crucial. Aiming that, we here report a portable PoC device based on Lens-free Interferometric Microscopy (LIM). The device employs hig...

Metasurfaces for molecular detection Although mid-infrared (mid-IR) spectroscopy is a mainstay of molecular fingerprinting, its sensitivity is diminished somewhat when looking at small volumes of sample. Nanophotonics provides a platform to enhance the detection capability. Tittl et al. built a mid-IR nanophotonic sensor based on reflection from an...

New healthcare initiatives including personalized medicine, global health, point-of-care diagnostic require breakthrough developments. I will introduce compact and high throughput biosensors enabled by metasurfaces interfaced with biology, chemistry.

Nanophotonics, and more specifically plasmonics, provides a rich toolbox for biomolecular sensing, since the engineered metasurfaces can enhance light–matter interactions to unprecedented levels. So far, biosensing associated with high-quality factor plasmonic resonances has almost exclusively relied on detection of spectral shifts and their associ...

Cell secretion dynamics play a central role in physiological and disease processes. Due to its various temporal profiles, it is essential to implement a precise detection scheme for continuous monitoring of secretion in real time. The current fluorescent and colorimetric approaches hinder such applications due to their multiple time-consuming steps...

The isolation of single biological cells and their further cultivation in dedicated arrayed chambers are key to the collection of statistically reliable temporal data in cell-based biological experiments. In this work, we present a hydrodynamic single cell trapping and culturing platform that facilitates cell observation and experimentation using s...

This letter reports on a novel fabrication method of 3D metal nanostructures using high-throughput nanostencil lithography. Aperture clogging, which occurs on the stencil membranes during physical vapor deposition, is leveraged to create complex topographies in nanoscale. Precision of the 3D nanofabrication method is studied in terms of geometric p...

This paper shows thermal measurement and analysis of a microfluidic device integrated with local thin film heater. Thermal analysis was calculated by finite element modeling. Electrical property of the micro heater was calibrated in advance of the thermal analysis due to the difference from the bulk property of Pt. The thermal analysis results agre...

This paper reports a simple and disposable polymer microwells chip to investigate single cell level of Red Blood Cells (RBCs) in parallel analysis with fast imaging. This method is based on the image processing method and microfluidic device that has microwells for single cell trapping. The RBCs are trapped in the microwells just by gravity. After...

This paper shows thermal measurement and analysis of a microfluidic device integrated with local thin film heater. Thermal analysis was calculated by finite element modeling. Electrical property of the micro heater was calibrated in advance of the thermal analysis due to the difference from the bulk property of Pt. The thermal analysis results agre...

The infrared (IR) spectrum lies between the microwave and optical frequency ranges, which are well suited for communication and energy harvesting purposes, respectively. The long wavelength IR (LWIR) spectrum, corresponding to wavelengths from 8 μm to 15 μm, includes the thermal radiation emitted by objects at room temperature and the Earth's terre...

In this paper, we demonstrate the micro heater device integrated with a micro chamber for investigation on cell-cell interactions under local thermal stimulation. The temperature distribution in the micro chamber was confirmed by on-chip temperature sensors and finite element method simulation. We successfully stimulated NIH-3T3 cells by Joule heat...

The infrared (IR) spectrum lies between the microwave and optical frequency ranges, which are well suited for communication and energy harvesting purposes, respectively. The long wavelength IR (LWIR) spectrum, corresponding to wavelengths from 8. μm to 15. μm, includes the thermal radiation emitted by objects at room temperature and the Earth's ter...

Asymmetric nano-bow-tie antennas offer the possibility of direct light-to-electrical energy conversion. These nano-antennas are easily integrated with Metal-Insulator-Metal (MIM) tunnel junctions in between the antenna segments for the purpose of coupled signal rectification. The architecture of the tunnel junction together with the antenna size pr...

Antenna coupled metal–insulator–metal (ACMIM) tunnel junctions are fast electromagnetic wave detectors shown to respond to radiation of wavelength as short as 1.6 μm. In the design and fabrication of these devices, it is crucial to keep the RC time constant of the tunnel junction small to achieve the requisite cut-off frequency and adequate rectifi...

Asymmetric thin-film metal-insulator-metal (MIM) tunneling diodes have been demonstrated using the geometric field enhancement (GFE) technique in a Ni/NiO/Ni structure. The GFE technique provides several benefits: generating asymmetric tunneling currents, lowering tunneling resistance, increasing nonlinearity, enhancing the effective ac signal ampl...

Electromagnetic wave rectification is demonstrated at 6 and 17 GHz in an asymmetric unbiased metal-semiconductor-metal tunneling diode that uses geometric field enhancement and traps in the tunneling barrier.

In this article, the authors show that geometric asymmetry in the layout of tunnel diodes yields asymmetry in the current-voltage (I-V) relationships associated with these diodes. Asymmetry improves diode performance. This effect is demonstrated for polysilicon– SiO ₂– Ti / Au and for Ni–NiO–Ni tunneling structures. For a polysilicon– Si...

A planar-type conductor-insulator-conductor tunneling diode is developed using a boiling water process for surface oxidation. First, microsized bow-tie patterns are transferred on a doped polysilicon layer using e-beam lithography. After reactive ion etching, the polysilicon bow-tie pattern has a very narrow knot between two triangles. Using a buff...

Our goal is to develop a rectifying antenna (rectenna) applicable to solar spectrum energy harvesting. In particular, we aim to demonstrate viable techniques for converting portion of the solar spectrum not efficiently converted to electric power by current photovoltaic approaches. Novel design guidelines are suggested for rectifying antenna couple...

Antenna-coupled tunnel junction diodes have recently been offering great advantages for IR and Terahertz detection applications. Fabrication has been a major constraint in our ability to field these devices. The first obstacle is the relatively small size of the antenna. As the length of the wave to be detected gets smaller, the size of the antenna...