Shift To Higher Frequencies Research Articles

Dependence of the ultrasound-caused shifts in optical frequency and phase and the modulation of optical phase in acousto-optic interaction of turbid media

In acousto-optic interaction, it is widely known that the frequency and phase of light are ultrasound-shifted in both transparent and turbid media, and furthermore the phase is also ultrasound-modulated in turbid media. However, it has been unclear whether there is an inherent relationship between the ultrasound-caused shifts in optical frequency and phase and the modulation of optical phase in turbid media. In the letter, we reveal that the ultrasound-caused shifts in optical frequency and phase depend on the modulation of optical phase in acousto-optic interaction of turbid media. Additionally, the intensity of frequency-shifted light is related to the modulation of optical phase. Then, with the increase of the modulation amplitude of optical phase, the phase-modulated light comprises relatively more light waves with higher frequency shifts. At last, the conclusions are confirmed by heterodyne experiments.

Transesterification catalyst strength as observed by solution-based oxygen-17 nuclear magnetic resonance spectroscopy

Natural abundance oxygen-17 nuclear magnetic resonance spectroscopy (17O-NMR) was applied to study homogeneous transesterification catalysts for fatty acid methyl ester production. Alkoxide catalysts were made with selected permutations of lithium, sodium, magnesium, and potassium hydroxides with ethanol, methanol, isopropanol, and glycerol. Pilot scale transesterification reactions of Canola oil were completed and the 17O-NMR spectra were collected from the reaction products. The alkoxide solutions showed the downfield shifts relative to the reagent alcohol, in a linear relationship with the concentration of catalyst ion. The electron deshielding of the oxygen of the alkoxide catalyst is observed directly by 17O-NMR, and the fastest catalyst has the largest downfield (high frequency) shift. This effect is most pronounced in potassium methoxide and less pronounced for less polar solvents such as isopropanol.

ISM band CPW-fed antenna for detection of skin cancer

A CPW-fed antenna sensor with high quality factor is designed to identify the skin cancer. The proposed antenna operates in the ISM band at 2.47 GHz frequency. The proposed antenna aims to exploit the variations in dielectric constants of skin, fat, and muscle tissues to enable non-invasive and early detection of skin cancer. The antenna design process involves considerations for achieving a high frequency shift and quality factor to discern subtle variations in dielectric properties. Electromagnetic simulations, utilizing advanced numerical techniques are employed to analyze the antenna's performance in different tissue environments. The proposed antenna design is optimized for enhancing its sensitivity to changes in the dielectric constants associated with healthy and cancerous skin tissues. To validate the antenna's effectiveness, experimental setups using tissue-mimicking phantoms are utilized. This research not only emphasizes the technical aspects of antenna design but also underscores the potential clinical applications for non-invasive skin cancer detection.

High resolution frequency shift measurement based on the time domain mode-locked optoelectronic oscillator

High resolution frequency shift measurement based on the time domain mode-locked optoelectronic oscillator

Electric Field-Assisted Molecularly Imprinted Polymer-Modified QCM Sensor for Enhanced Detection of Immunoglobulin.

In this study, an electric-field-assisted molecularly imprinted polymer (EFAMIP) as an enhanced form of MIP was developed to improve the MIP-modified quartz crystal microbalance (QCM) biosensors. While exerting a vertical electric field, polymerization of methacrylic acid in the presence of immunoglobulin G (IgG) as the template was initiated, and later, after the template removal process, the EFAMIPs were obtained. The polymer surface characterization was conducted by using a scanning electron microscope. The impact of electric field direction on IgG binding sites, forming either EFAMIP-Fab or EFAMIP-Fc, was assessed. Next, the static measurement results in liquid for EFAMIP-modified QCM and MIP-modified QCM were compared. While encompassing IgG, EFAMIP-modified QCMs exhibited up to a 113.5% higher frequency shift than typical MIP in time-limited detection. The final frequency shift of EFAMIP, which determines the detection limit of IgG, was improved up to 12.5% compared to typical MIP. Moreover, the EFAMIP-Fab performance was promising for the selective detection of IgG in a solution containing different types of immunoglobulins.

High power tunable Raman fiber laser at 1.2 μm waveband

Development of a high power fiber laser at special waveband, which is difficult to achieve by conventional rare-earth-doped fibers, is a significant challenge. One of the most common methods for achieving lasing at special wavelength is Raman conversion. Phosphorus-doped fiber (PDF), due to the phosphorus-related large frequency shift Raman peak at 40 THz, is a great choice for large frequency shift Raman conversion. Here, by adopting 150 m large mode area triple-clad PDF as Raman gain medium, and a novel wavelength-selective feedback mechanism to suppress the silica-related Raman emission, we build a high power cladding-pumped Raman fiber laser at 1.2 μm waveband. A Raman signal with power up to 735.8 W at 1252.7 nm is obtained. To the best of our knowledge, this is the highest output power ever reported for fiber lasers at 1.2 μm waveband. Moreover, by tuning the wavelength of the pump source, a tunable Raman output of more than 450 W over a wavelength range of 1240.6–1252.7 nm is demonstrated. This work proves PDF’s advantage in high power large frequency shift Raman conversion with a cladding pump scheme, thus providing a good solution for a high power laser source at special waveband.Graphical

High-Frequency Shift and Extension of the Terahertz Radiation Spectrum up to 10 THz During Optical Rectification of High-Power Few-Cycle Near-Infrared Femtosecond Pump Radiation in a BNA Crystal

The generation of terahertz radiation in a BNA crystal pumped by 1.24-µm femtosecond laser radiation from a Cr:forsterite laser system with a pulse duration of 100 and 35 fs and a pump density of 10 mJ/cm2 has been realized. The achieved generation efficiency is 0.1%. It is found that a decrease in the pump pulse duration from 100 to 35 fs leads to the generation of high-frequency components in the ranges of 2.5–6.5 THz and 9‒10.5 THz in the generated radiation spectrum. Simulation of the terahertz radiation generation based on the solution of Maxwell’s equations by the finite-difference time-domain method has made it possible to adequately describe the measured spectra. The generation of broadband high-frequency terahertz radiation in the BNA crystal pumped by the Cr:forsterite laser system allows one to consider this schematic as an alternative to sources based on the BNA crystal pumped by a Ti:sapphire laser system.

High-Frequency Shift and Extension of the Terahertz Radiation Spectrum up to 10 THz During Optical Rectification of High-Power Few-Cycle Near-Infrared Femtosecond Pump Radiation in a BNA Crystal

The generation of terahertz radiation in a BNA crystal pumped by 1.24-µm femtosecond laser radiation from a Cr:forsterite laser system with a pulse duration of 100 and 35 fs and a pump density of 10 mJ/cm2 has been realized. The achieved generation efficiency is 0.1%. It is found that a decrease in the pump pulse duration from 100 to 35 fs leads to the generation of high-frequency components in the ranges of 2.5–6.5 THz and 9‒10.5 THz in the generated radiation spectrum. Simulation of the terahertz radiation generation based on the solution of Maxwell’s equations by the finite-difference time-domain method has made it possible to adequately describe the measured spectra. The generation of broadband high-frequency terahertz radiation in the BNA crystal pumped by the Cr:forsterite laser system allows one to consider this schematic as an alternative to sources based on the BNA crystal pumped by a Ti:sapphire laser system.

Electron-beam-driven plasma wakefield acceleration of photons

The paper [R .T. Sandberg and A. G. R. Thomas, Phys. Rev. Lett. 130, 085001 (2023)] proposed a scheme to generate ultrashort, high energy pulses of XUV photons through dephasingless photon acceleration in a beam-driven plasma wakefield. An ultrashort laser pulse is placed in the plasma wake behind a relativistic electron bunch so that it experiences a density gradient and therefore shifts up in frequency. Using a tapered density profile provides phase-matching between the driver and witness pulses. In this paper, we study via particle-in-cell simulation the limits, practical realization, and 3D considerations for beam-driven photon acceleration using the tapered plasma density profile. We study increased efficiency by the use of a chirped drive pulse, establishing the necessity of the density profile shape we derived as opposed to a simple linear ramp, but also demonstrating that a piecewise representation of the profile—as could be experimentally achieved by a series of gas cells—is adequate for achieving phase matching. Scalings to even higher frequency shifts are given.

Optical frequency shifted FMCW Lidar system for unambiguous measurement of distance and velocity

A new frequency-modulated continuous-wave (FMCW) Lidar system is proposed to measure distance and velocity unambiguously by using a frequency-shifted probe light. The optical frequency shift is induced by an acousto-optic modulator (AOM). The generated beat signal is up converted to high frequency, sparing sufficient RF bandwidth to avoid signal aliasing caused by high Doppler frequency shifts. The aliasing-free beat signal thus can be used to extract distance and velocity information unambiguously. Here, we experimentally demonstrated real-time measurement on a disk spinning up to 26.43 m/s at 1.267 m away. The precision of the measured distance and velocity are 16 mm and 0.037 m/s respectively. Furthermore, the proposed scheme is capable of discriminating the direction of rotation based on a single Fast Fourier Transform analysis. In addition, we apply a free space circulator to the system to weaken the mirror-scattered signals and thus to achieve continuous measurement of beats signal over wide frequency range. Finally, a three-dimensional image of the spinning disk is reconstructed.

Enabling Variable High Spatial Resolution Retrieval From a Long Pulse BOTDA Sensor

Spatial resolution (SR) is one of the most important parameters of Brillouin optical time-domain analysis (BOTDA) sensors, which determines the minimum length that a perturbation event can be distinguished. In the field of Internet of Things (IoT), there is an urgent need for sensors with large-scale high-precision sensing capability for scenarios, such as intelligent monitoring of production lines and urban infrastructure. Conventionally, the SR is normally restricted to be longer than 1 m due to the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10$ </tex-math></inline-formula> -ns acoustic lifetime limitation in silica optical fibers. For long-distance smart monitoring systems, the SR is generally on the order of several meters or even worse. However, it does not meet the needs of many applications. Therefore, there is an urgent need to achieve SR in the submeter magnitude. In this work, for the first time to the best of our knowledge, we propose a convolutional neural network (CNN) to process the data of conventional BOTDA sensors, which achieves unprecedented performance improvement that allows to directly retrieve submeter SR from the sensing system that use long pump pulses. By using the simulated Brillouin gain spectrums (BGSs) as the CNN input and the corresponding high SR Brillouin frequency shift (BFS) as the output target, the trained CNN is able to obtain an SR higher than the theoretical value determined by the pump pulse width. In the experiment, the CNN accurately retrieves 0.5-m hotspots from the measured BGS with pump pulses from 20 to 50 ns, and the acquired BFS is in great agreement with 45/40 ns differential pulse-width pair (DPP) measurement results. Compared with the DPP technique, the proposed CNN demonstrates a twofold improvement in BFS uncertainty with only half the measurement time. In addition, by changing the training data sets, the proposed CNN can obtain tunable high SR retrieval based on conventional BOTDA sensors that use long pulses without any requirement of hardware modifications. It is worth mentioning that the proposed method is also applicable to larger pulse widths to retrieve a submeter SR. The proposed data post-processing approach paves the way to enable novel high SR BOTDA sensors, which brings substantial improvement over the state-of-the-art techniques in terms of system complexity, measurement time, reliability, etc.

Identification of an efficient adsorbent for ethanol sensing at room temperature using quartz crystal microbalance

Zeolite coated quartz crystal microbalance (QCM) is proposed as an efficient sensor for the detection of ethanol at room temperature. In this work, three zeolites DaY, ZSM-5, and BEA were investigated in order to determine the most efficient adsorbent for ethanol sensing at room temperature. The sensing performances were found to be mostly influenced by the acid site density and the zeolite's pore size. The BEA coated QCM sensor exhibited the best performances with a high relative frequency shift from 9.0 × 10−7 to 2 × 10−6 for 10 ppm of ethanol. Furthermore, this sensor exhibited fast response and recovery times which makes it a suitable material for the monitoring of ethanol in the air. In addition, the ethanol diffusion order was evaluated using Fickian diffusion law and was found to be the highest for the zeolite BEA. A sensing mechanism was also proposed for the adsorption and desorption of ethanol into zeolites based on unstable protonated dimers, water and diethyle ether resides for the energy-efficient ethanol sensor.

A V-Shaped Microcantilever Sensor Based on a Gap Method for Real-Time Detection of E. coli Bacteria

This paper presents a dynamic-mode microcantilever sensor based on a gap method. The sensor has a V-shaped microcantilever and a fixed structure at a distance of 2 µm from its free end. The microcantilever is excited by applying an ac electric potential (3 Vp) to its piezoelectric pads and vibrates at its fundamental resonant frequency. An independent ac electric potential (200 kHz, 15 Vpp) is applied to the fixed structure. This creates a non-uniform electric field with its maxima at the gap and exerts a dielectrophoresis (DEP) force. The DEP force attracts and adsorbs the E. coli bacteria to the cantilever edge at the gap. The binding of the bacteria to the cantilever creates a shift in the resonant frequency of the microcantilever sensor, which is detected by a laser vibrometer. The real-time detection of E. coli bacteria samples, diluted in distilled water, was performed for concentrations of 105–103 cells/mL and the real-time frequency shifts were −2264.3 to −755 Hz in 4 min, respectively. The tests were expanded to study the effect of the electric potential amplitude (10, 12, 15 Vpp) and higher frequency shifts were observed for higher amplitudes.

Coherent optical processes on Cs D2 line magnetically induced transitions

The increased spectral resolution allowed by the use of extremely thin vapor cells has led to the observation of interesting behavior of alkali transitions when placed in a magnetic field. Particularly, the probabilities of transitions obeying an apparent Fe−Fg≡ΔF=±2 selection rule, referred to as magnetically-induced (MI) transitions, largely increase in the intermediate interaction regime while being null at zero and higher magnetic fields. With an 800 nm-thick Cs vapor cell placed in a field up to 1.5 kG, we show here that the generation of electromagnetically induced transparency (EIT), realized in Λ-systems involving ΔF=−2 MI transitions, is only possible when both the coupling and probe beams are σ−-circular polarized, demonstrating that EIT is affected by magnetic circular dichroism. A similar rule of thumb can be extrapolated for ΔF=+2 MI transitions and σ+ polarization. Because of the high frequency shift slope (typ. 4 MHz/G), the generation of EIT resonances involving MI transitions is interesting, especially in the context of growing attention towards micro-machined alkali vapor cell sensors.

Low-complexity OTFS-based hybrid precoding in mmWave high mobility systems

The integration of aircraft into air-to-ground (A2G) communications with a variety of applications has attracted much attention, and it is critical to establish reliable communication links in A2G systems. However, suffering from the multipath effects and high Doppler frequency shifts, the quality of the transmission links is severely degraded in high mobility scenarios. To overcome the performance degradation caused by the double selective channel, a new modulation technique called orthogonal time-frequency-space (OTFS) is proposed recently. Moreover, millimeter wave (mmWave) massive multiple-input-multiple-output (MIMO) precoding is a simple and effective method to improve the system performance. Unfortunately, most of the existing MIMO-OTFS studies are implemented on the full-digital architecture, which will lead to high power consumption and high hardware cost. Besides, with the assumption of the practical waveforms in OTFS systems, it is complicated to work out the precoding algorithm. The objective of this paper is to develop a low-complexity OTFS-based hybrid precoding algorithm with rectangular waveforms for mmWave A2G communications. We first establish the delay-Doppler (DD) domain signal transmission process in hybrid precoding and derive the equivalent baseband DD domain channel matrix. Next, a two-stage hybrid precoding algorithm is proposed, in which the analog precoder based on steering vector is designed, and the recursive digital precoding algorithm is explored. Then a matrix approximation-based strategy is discussed to further reduce complexity. Furthermore, the computational complexity of the proposed algorithm is analyzed. Finally, the numerical results show the lower complexity and superior bit error rate performance of the proposed algorithm compared with the existing OTFS algorithms in high mobility scenarios.

Microwave sensor for liquid classification and permittivity estimation of dielectric materials

This paper presents a material detection sensor based on SIW technique. Three electric walls of the SIW cavity resonator are made by metallic vias whereas the fourth one is made by λg4 stub. The dielectric substrate under stub is partially removed and by immersing this empty space inside the cup filled with the liquid under test or by inserting the dielectric material inside the sensor, the effective permittivity of the medium under stub will change, shifting the resonant frequency of the cavity resonator. These shifts are taken as an indicator of presence of the liquid or the dielectric material. An analytical model based on mixing rule formula is presented and the obtained result is compared with the simulated one. The comparison indicated that the analytical model is an accurate approximation method of this proposed sensor. In addition, the measurement results showed that the proposed sensor can detect a large dynamic range of permittivity ranging from 1 to 83 and has a high frequency shift (296 MHz). The unique feature of this sensor can be that by changing the volume of the MUT by changing the length of the empty space under stub, the dynamic range and the sensitivity increase greatly.

Low pilot overhead channel estimation for CP‐OFDM‐based massive MIMO OTFS system

In high-speed mobile scenarios, due to the high-speed relative motion between transmitter and receiver, the high Doppler frequency shift interferes with the inter-subcarrier orthogonality in orthogonal frequency-division multiplexing (OFDM) systems. Therefore its performance is significantly degraded. Recently, orthogonal time–frequency space (OTFS) is considered as an effective alternative scheme to OFDM for time-varying channels. As with OFDM-massive multiple input multiple output (MIMO) systems, downlink channel estimation is necessary for OTFS-massive MIMO systems to improve the spectral efficiency in frequency-division duplex (FDD) mode without channel reciprocity. Here, first the cyclic prefix -OFDM-based massive MIMO OTFS system channel with antenna directivity pattern is analyzed, and transform the burst sparsity in the angle domain into block sparsity by using non-uniform Fourier transform (NUFT). Furthermore, to solve the problem that the pilot overhead grows linearly with the number of antennas, we propose a three-dimensional (3D) dynamic support detect (DSD) algorithm. Compared with the traditional OMP algorithm, and the 3D-structured orthogonal matching pursuit algorithm, simulation results demonstrate the proposed DSD algorithm has higher channel estimation accuracy, and lower pilot overhead.

Разработка математической модели интерферометрической системы определения доплеровского сдвига частоты.

This work presents the result of the received signal measuring system for processing Doppler frequency theoretical research. In the researching device means of controlling laser frequency whose amplitude is proportional to the Doppler frequency shift of the received RF signal is realized. The coherent laser beam is divided in two forming interference pattern. In this case, one of the beams passes through the delay line, which leads to a phase shift in the optical wave. The rate of this phase shift is proportional to the laser frequency, changes in which cause corresponding changes in the interference pattern. Changes in the interference pattern in center analysis makes it possible to determine the changes of the laser frequency, which depends on Doppler frequency shift of the received RF signal. In this work opposition of the requirements for the Doppler frequency shift determination interferometric system parameters (the coefficient of proportionality to conversion Doppler frequency shift of the received RF signal in laser frequency and time delay) is discovered: large dynamic measurement range and high Doppler frequency shift measurement resolution. The processing the received RF signal method is proposed. This method take into consideration these requirements. The proposed measurement algorithm implements the multiscale principle. It is pointed that the proposed processing the measurements results method can be implemented both the parallel processing in channels with different values of conversion coefficients, and sequential – with their iterative change.

A Driftwood‐Based Record of Arctic Sea Ice During the Last 500 Years From Northern Svalbard Reveals Sea Ice Dynamics in the Arctic Ocean and Arctic Peripheral Seas

AbstractWe present a 500‐year history of naturally felled driftwood incursion to northern Svalbard, directly reflecting regional sea ice conditions and Arctic Ocean circulation. Provenance and age determinations by dendrochronology and wood anatomy provide insights into Arctic Ocean currents and climatic conditions at a fine spatial resolution, as crossdating with reference chronologies from the circum‐Arctic boreal forests enables determination of the watershed the driftwood originated from. Sample crossdating may result in a wide range of matches across the pan‐boreal region, which may be biased toward regions covered by the reference chronologies. Our study considers alternate approaches to selecting probable origin sites, by weighting scores via reference chronology span and visualizing results through spatiotemporal density plots, as opposed to more basic ranking systems. As our samples come from naturally felled trees (not logged or both), the relative proportions of different provenances are used to infer past ocean current dominance. Our record indicates centennial‐to decadal‐scale shifts in source regions for driftwood incursion to Svalbard, aligning with Late Holocene high variability and high frequency shifts in the Transpolar Drift and Beaufort Gyre strengths and associated fluctuating climate conditions. Driftwood occurrence and provenance also track the northward ice formation shift in peripheral Arctic seas in the past century. A distinct decrease in driftwood incursion during the last 30 years matches the observed decline in pan‐Arctic sea ice extent in recent decades. Our new approach successfully employs driftwood as a proxy for Arctic Ocean surface circulation and sea ice dynamics.

Molecularly Imprinted Polymers for Recognition of Engineered Nanoparticles

Introduction Engineered nanoparticles (ENPs) have found widespread use in modern technology, medicine and daily life. Ag-NPs for example are used as antimicrobials in several medical and cosmetic products, whereas Au-NPs have attracted great interest in medical applications, such as drug delivery systems. However, ENPs can potentially cause adverse toxic effects due to their small size and high surface to volume ratio and their increased utilization in different medical and consumer products leads to an increased exposure to humans. While a range of state-of-the-art technologies, such as ICP-MS, is available for the detection of ENPs, they usually require thorough sample preparation, highly trained personnel and expensive equipment. [1] To circumvent these limitations, the use of artificial recognition materials, as for instance molecularly imprinted polymers (MIPs), is a promising alternative. MIPs are synthesized via (radical) polymerization in the presence of template molecules. After template removal, cavities, which are complementary to the template in size, shape and chemical functionality, form in the material. These can rebind target molecules with high sensitivity and selectivity. [2] MIPs can be used as receptors for quartz-crystal microbalances (QCMs), which are mass-sensitive transducers that measure a change in mass via a change in resonant frequency of the oscillating quartz. [3] In this work, we report on developing an easy-to-use and low-cost MIP-based QCM sensor for the detection of ENPs in aqueous matrices. Method Stamps with immobilized metal-based NPs were used to imprint template material on poly(styrene-co-EGDMA) layers. Particle distribution and shape of NPs, immobilized on PDMS stamps, were analyzed using atomic force microscopy (AFM). MIPs were prepared by pressing NP-stamps onto poly(styrene-co-EGDMA) thin films. After polymerization overnight, stamps were removed from the polymers and MIPs were characterized via AFM and QCM. For QCM measurements, we utilized an in-house dual-electrode system. In this case, one of the two electrode pairs served as reference and was coated with the non-imprinted polymer (NIP) to compensate for unspecific binding and external effects, such as temperature changes. Results and Discussion Two different substrates were tested for fabrication of NP stamps: glass and PDMS. In both cases, APTES was used as linker for NP immobilization and let to desired cavity formation on MIPs as assed via AFM. However, removal of glass stamps was challenging, as a result of the strong interaction between glass NP stamp and the polymer, and required applying rather strong force to remove NP stamps. PDMS led to better outcomes and was easily removable from MIPs, which is especially useful for QCMs due to their fragility. QCM measurements of poly(styrene-co-EGDMA) MIPs, imprinted with Ag-NPs (75 nm, PVP-stabilized), led to high sensor responses of up to 1 kHz, whereas no binding was observed on the NIP. QCMs were analyzed via AFM before and after frequency measurements (figures 1a-d). As shown in figure 1a, cavities matching the template in size and shape were distributed evenly across the MIP surface, whereas the NIP did not reveal any binding sites (1c). After QCM measurement and exposure of MIPs and NIPs to the imprinted Ag-NPs, re-binding occurred exclusively on the MIP as visible in figures 1b and 1d, confirming successful NP imprinting. First selectivity studies of poly(styrene-co-EGDMA) MIPs seem promising: exposure to smaller Ag-NPs (50 nm) resulted in no re-incorporation of particles on sensing layers. However, measurement of Au-NPs on Ag-NP MIPs, imprinted with particles of the same size and stabilizer shell as the Au-NPs, led to re-binding on the MIP. Those results were not surprising since both NPs had the same size, shape and surface chemistry, and used Au-NPs fitted perfectly into the Ag-NP cavities. However, there is still room for improvement regarding batch-to-batch reproducibility. Further characterization of these sensing materials is necessary and still ongoing. Conclusion and Outlook Imprinting of thin polymer-films using metal-based ENPs is a novel concept with considerable potential in the field of sensor technology. Poly(styrene-co-EGDMA) Ag-NP MIPs were prepared by surface imprinting and characterized using AFM, revealing corresponding NP cavities on the polymer surface and thus confirming successful imprinting of NPs. Moreover, QCM measurements of MIPs led to sensor responses with high frequency shifts upon exposure to the imprinted particles with no cross-selectivity to smaller NPs. In the near future, selectivity studies will be completed in order to assess binding responses as a function of NP size, stabilizer and core material. Overall, this work demonstrates the potential use of MIPs for analysis of NPs in complex matrices, such as food, cosmetic or medical products. However, since biding occurred in an irreversible manner, MIPs would probably be more suitable as filtration materials rather than sensing layers, unless a way is found in order to remove NPs from the cavities again. Acknowledgements This work has been funded by the Austrian Science Fund FWF, project number I 3568-N28, which we gratefully acknowledge.