Ambient Electromagnetic Fields Research Articles

On the Quasistationarity of the Ambient Electromagnetic Field Generated by Wi-Fi Sources

In recent decades, the widespread use of mobile phones and wireless technologies has led to a significant increase in radiofrequency electromagnetic fields (RF-EMFs), raising concerns about continuous RF-EMF exposure among the general population. Recent research indicates that real-life RF signals are more biologically active than controlled laboratory signals with a low variability, suggesting that living organisms can adapt to EMF exposure when the pattern has a low variability. However, using real-life sources with unpredictable variation signals in biological experiments contradicts the principle of experiment controllability. This paper aims to investigate the nature of signals generated by current sources of ambient EMFs in terms of stationarity, with the goal of replicating them in biological experiments to study the effects of EMF exposure. Employing a range of statistical methodologies, starting with descriptive statistical analysis and progressing to the advanced APDP and APTF methods, an examination is conducted on a collection of Wi-Fi signal recordings across various operating modes, with particular attention given to video streaming. The chosen datasets are scrutinized with respect to their adherence to a Gaussian distribution and the concept of stationarity. The results indicate that the observed Wi-Fi signals lack stationarity in both the time and frequency domains. However, based on the analytical findings, it is possible to generate signals in frequency that authentically replicate Wi-Fi signals, accounting for nonstationarity considerations.

Formula omitted]-soliton asymptotic analysis on the Gerdjikov–Ivanov equation for the Alfvén waves in a plasma

Gerdjikov–Ivanov equation describes the propagation of the weakly nonlinear and dispersive Alfvén waves along the ambient electromagnetic field in a partially ionized plasma in the presence of the Hall, ambipolar, and Ohmic effects. With respect to the transverse components of the electromagnetic field to the lowest order, N solitons in the determinant form are derived and analyzed via the asymptotic analysis on the basis of an existing binary DT and an existing Lax pair, where N is a positive integer. Without loss of generality, expressions of the N asymptotic solitons in the determinant form are obtained, from which we can obtain the amplitudes, positions, velocities and phase shifts of the N asymptotic solitons. Those results reveal that the interaction among the N solitons is elastic. When N=3, we graphically illustrate the elastic interaction among the three solitons. This work may provide a physical mechanism for the generations and interactions of the Alfvén solitons in the magnetized plasmas.

An efficient dual-scale method for analysis of EMI problems resulted from radiation sources

An efficient dual-scale method, which integrates parabolic equation (PE) with electric field integral equation (EFIE) formulated via the Rao-Wilton-Glisson moment method (RWG-MOM), is proposed to analyze the electromagnetic interference (EMI) problems resulted from radiation sources. This method is implemented by decomposing the original intractable multi-scale problem domain into two sub-regions: (1) modeling of the complicated ambient electromagnetic fields by PE and (2) solution of the fields coupling to the exposed electronic devices by RWG-MOM. Frequency-sweep and Fourier synthesis techniques are applied to calculate the transient currents and voltages. The proposed method is able to fully model the disturbances of the electromagnetic fields by multi-path effects. Besides, it reduces the memory footprint and the CPU computing time effectively compared to the traditional full-wave electromagnetic methods. Numerical examples are presented, and the simulation results indicate that this method is well suitable for the EMI analysis of external radiation sources.

Photons from dark photon solitons via parametric resonance

Wave-like dark matter made of spin-1 particles (dark photons) is expected to form ground state clumps called “vector solitons”, which can have different polarizations. In this work, we consider the interaction of dark photons with photons, expressed as dimension-6 operators, and study the electromagnetic radiation that arises from an isolated vector soliton due to parametric resonant amplification of the ambient electromagnetic field. We characterize the directional dependence and polarization of the outgoing radiation, which depends on the operator as well as the polarization state of the underlying vector soliton. We discuss the implications of this radiation for the stability of solitons and as a possible channel for detecting mergers of vector solitons through astrophysical observations.

Cow dung ash (CDA): A sustainable conductive filler for enhancing electromagnetic shielding property of cement mortar

Cow Dung ash (CDA) is a wide spread farm by-product, generated by burning dry cow-dung. Cement mortar, the work horse of construction industry inherently possesses significant electrical conductivity, thereby providing considerable electromagnetic shielding property. CDA is investigated as novel sustainable conductive filler, as sand replacement, for enhancing electromagnetic shielding property of cement mortar. The electromagnetic properties of CDA are determined employing standard wave guide techniques, in X band, and electrical conductivity around 10-2 S/m is observed. The electrical loss tangent is observed around 0.2–0.3. Cement mortar slabs with CDA as sand replacement are prototyped. Sand replacement till 15 % by volume is investigated. Considerable reduction in compressive strength is reported in literature for sand replacement beyond 15 %. After 28 days of curing, the prototyped slabs are subjected to electromagnetic shielding effectiveness determination, as per ASTM 4935 two antenna standard, in the X band of frequencies centred around 10 GHz. Shielding Effectiveness (SE) around 7 dB is observed for 3 % CDA as sand replacement, around 10 dB for 10 % replacement, and around 20 dB for 15 % CDA. Compressive strength measurement employing Universal Testing machine presented significant reduction in compressive strength as CDA replacement tend towards 15 %. Employing CDA loaded cement mortar for plastering, is a low cost, easy deployable solution for realizing customized electromagnetic shielding levels in buildings housing critical electrical and electronic infrastructure including servers and data centres. Realizing low cost, easy deployable customized shielding solutions is an upcoming research domain, primarily due to the anticipated increase in ambient electromagnetic field levels in our surroundings caused by the rampant deployment of communication technologies including 5G and IoT. Apart from providing positive environmental impact, acting as sand replacement, enhanced CDA utilization by engineering sectors can lead to good revenue generation model for rural economic development.

AC interference impact on EIS assessment of organic coatings using dummy cells, calibration foils and field exposed coated samples

Field application of EIS to intact and scarcely degraded high-performance protective coatings is challenging because of ambient electromagnetic fields, which cause stochastic variations in the phase angle and, to a lesser extent, in the impedance modulus of the coating spectra. AC interferences with amplitudes between 10 and 800 mV were induced on dummy cells and calibration foils to systematically investigate the effects of interference impact on the accuracy and precision of measurements with the EIS setup intended for use on coatings in the field. For EIS signal amplitudes between 10 and 250 mV and the AC interference amplitudes ≤250 mV, the measurement accuracy and precision were limited by the synergistic influence of the AC interferences and the imprecision of the EIS instrument. For systems with impedance ≥ GΩ, the accuracy of the impedance logarithm was 97.8% at signal amplitudes ≥190 mV, and the precision increased from nearly 95% to 99% as the signal amplitude increased from 10 to 150 mV, indicating that very accurate and precise measurements can be obtained at higher signal amplitudes. An example of EIS measurements on coated samples exposed in the area of AC railway interferences is given. Although the quantitative conclusions may be instrument specific, they reflect well the declared capabilities of today's high-end EIS devices. The universal explanation is given in the context of equivalent circuit theory of the observed scatter in the EIS spectral data. The coating assessment was commented on in terms of the unique properties of the mean and relative standard deviation of impedance expressed on the logarithmic scale.

Active principle in potentised medicines: Nanoparticle versus quantum domain – An overview

Background: The fact that homoeopathic medicines act even at very high dilutions has created a confusion amongst scientists. This led to different models such as formation of nanoparticles and memory of water. The basic question 'what is responsible for physiological activity of homoeopathic medicines' is yet to be answered conclusively. Objective: The objective of this overview was to find out if formation of nanoparticles or creation of quantum domain in the medium is responsible for the physiological activity of homoeopathic medicines. Methods: This overview is based on the experiments done between 2004 and 2019. Results: The succussion of the medicine has the following effects: i. At high potency, due to the mechanical energy transferred to the system, the size of the substrate reduces to nanodimension increasing membrane permeability. Furthermore, they affect several electrical properties of an electroactive polymer and enhance thermovoltage generation. ii. In the presence of an ambient electromagnetic field, domains composed of the vehicular polar molecules are formed, which bear the signature of the dissolved solute. The domains are sources of quasi-free electrons which are manifested in voltage generation separating two different polar media. The structured water also explains the ultraviolet–visible (UV-Vis) spectra. Conclusion: In high potency, formation of nanoparticles explains the effect of homoeopathic medicines on properties such as permeability, electrical properties of polymers and thermovoltage generation, whereas formation of domains in the vehicle medium explains properties such as voltage generation separating two different polar media and UV-Vis spectra.

Developmental Effects of ELF-EMF on Testis and Ovary in Newborn Rats

Background and Objective: Human beings are unavoidably exposed to ambient electromagnetic fields (EMF) generated from various electrical devices and from power transmission lines. Controversy exists about the effects of EMF on various organs. The aim of this work evaluation the effects of intrauterine exposure to 50Hz electromagnetic field (EMF) on testicular and ovary development. Methods: Pregnant wistar rats were exposed to 3mT, EMF for 21 days, 4 hours/day. Pregnant rats under same condition of treatment group, but off the field as a sham group intended and pregnant rats were used as control in the room. After delivery, testis and ovary were removed from male and female pups, fixed and prepared for light microscopic studies. Results: Microscopic results revealed seminiferous tubules in treatment group in comparison with the control and sham groups were widely separated from each other, in this group in seminiferous tubules vacuolization, detachment of gonocytes from each other, heterochromatic gonocytes and decreasing in interstitial tissue was found. The ovary of the treatment group in comparison to control group showed that oocyte nests were mostly broken and irregularly arranged. The primordial follicles were less developed. Conclusion: In general, as a result of the exposure to EMF during early developmental period, morphological changes in testicular and ovary development were evident, that may well extend till adult stage and may affect fertility.

Stimulated Hawking emission from electromagnetic analogue black hole: Theory and observation

In this paper we consider possible analogue Hawking radiation from a normal dielectric and metamaterial composite, having an analogue horizon where the dielectric parameters vanish and change sign upon crossing this transition zone. We follow a complex path analysis to show the presence of an analogue Hawking temperature at the horizon and subsequent photon production from the ambient electromagnetic field. Possibility of experimental observation is also commented upon.

Electromagnetic interaction between the power distribution grid and thE HV system of an electric vehicle

In the paper it will be presented the history of electric vehicles (EVs), compared to conventional combustion engine cars. Environmental impacts produced the necessity of a cleaner transportation by reintroducing electrical cars in the automotive market. By increasing the EVs used in transportation, the level of pollution is decreased, but some major issues concerning electromagnetic compatibility are raised. The ambient electromagnetic field was described, focusing on simulation of a MV power distribution line. Afterwards, it was analyzed the electromagnetic interaction between an electric vehicle and the power distribution line, simulating the magnetic field distribution.

A Novel Dual-Rotor Ultrasonic Motor for Underwater Propulsion

Micro underwater vehicles (MUVs) have been highlighted recently for underwater explorations because of their high maneuverability, low price, great flexibility, etc. The thrusters of most conventional MUVs are driven by electromagnetic motors, which need big mechanical transmission parts and are prone to being interrupted by the variance of ambient electromagnetic fields. In this paper, a novel dual-rotor ultrasonic motor with double output shafts, compact size, and no electromagnetic interference is presented, characterized, and applied for actuating underwater robots. This motor was composed of a spindle-shaped stator, pre-pressure modulation unit, and dual rotors, which can output two simultaneous rotations to increase the propulsion force of the MUV. The pre-pressure modulation unit utilized a torsion spring to adjust the preload at the contact faces between the stator and rotor. The working principle of the ultrasonic motor was developed and the vibration mode of the stator was analyzed by the finite element method. Experimental results show that the no-load rotary speed and stalling torque of the prototype ultrasonic motor were 110 r/min and 3 mN·m, respectively, with 150 V peak-to-peak driving voltage at resonance. One underwater robot model equipped with the proposed ultrasonic motor-powered thruster could move at 33 mm/s immersed in water. The dual-rotor ultrasonic motor proposed here provides another alternative for driving MUVs and is appropriate for developing specific MUVs when the electromagnetic interference issue needs to be considered.

Design and Measurement of 3D Flexible Antenna Diversity for Ambient RF Energy Scavenging in Indoor Scenarios

Ambient radiofrequency (RF) energy scavenging has been recently addressed with a wide range of studies to provide alternative powering for low-power applications. However, due to the low power level of the ambient electromagnetic field, the efficiency of the latter systems is still below expectations. Multipath in the environment may be considered and antenna diversity is then a solution for quasi-omnidirectional RF reception to reach a higher probability of receiving energy in a realistic situation. A 3D flexible antenna diversity, which can be integrated into the rectangular packaging, is proposed in order to take advantage of system packaging form. The angle and polarization diversity antenna was designed on flexible substrate in order to achieve the flexibility and low-cost. This design overcomes the low performance of the substrate while maintaining a compact, high isolation, and good radiation efficiency of the antenna. An indoor experimental setup was carried out to compare different rectenna configurations. The measurement results validate the principle and demonstrate the performance of the 3D flexible diversity system. The probability measurements were carried out under precise conditions in indoor scenarios and the results in comparison with statistic models confirmed the performance of the system in such low power conditions.

Electromagnetic fields may act via calcineurin inhibition to suppress immunity, thereby increasing risk for opportunistic infection: Conceivable mechanisms of action

While a good number of studies have demonstrated that modern, man-made ambient electromagnetic fields can have both stimulatory and inhibitory effect on immune system function, the precise mechanisms have yet to be completely elucidated. It is hypothesized here that, depending on the parameters, one of the means by which long-term electromagnetic field exposure has the potential to eventually lead to immunosuppression is via downstream inhibition of the enzyme calcineurin — a protein phosphatase, which activates the T-cells of the immune system and can be blocked by pharmaceutical agents.Calcineurin is the target of a class of pharmaceuticals called calcineurin inhibitors (e.g., cyclosporine, pimecrolimus and tacrolimus). When organ transplant recipients take such pharmaceuticals to prevent or suppress organ transplant rejection, one of the major side effects is immunosuppression leading to increased risk of opportunistic infection: e.g., fungal, viral (Epstein-Barr virus, cytomegalovirus), atypical bacterial (Nocardia, Listeria, mycobacterial, mycoplasma), and parasitic (e.g., toxoplasmosis) infections.Frequent anecdotal reports, as well as a number of scientific studies, have shown that electromagnetic field exposures may indeed produce the same effect: a weakened immune system leading to an increase in the same or similar opportunistic infections: i.e., fungal, viral, atypical bacterial, and parasitic infections.Furthermore, numerous research studies have shown that man-made electromagnetic fields have the potential to open voltage-gated calcium channels, which can in turn produce a pathological increase of intracellular calcium, leading downstream to the pathological production of a series of reactive oxygen species. Finally, there are a number of research studies demonstrating the inhibition of calcineurin by a pathological production of reactive oxygen species.Hence, it is hypothesized here that exposures to electromagnetic fields have the potential to inhibit immune system response by means of an eventual pathological increase in the influx of calcium into the cytoplasm of the cell, which induces a pathological production of reactive oxygen species, which in turn can have an inhibitory effect on calcineurin. Calcineurin inhibition leads to immunosuppression, which in turn leads to a weakened immune system and an increase in opportunistic infection.

Explicitly covariant dispersion relations and self-induced transparency

Explicitly covariant dispersion relations for a variety of plasma waves in unmagnetized and magnetized plasmas are derived in a systematic manner from a fully covariant plasma formulation. One needs to invoke relatively little known invariant combinations constructed from the ambient electromagnetic fields and the wave vector to accomplish the program. The implication of this work applied to the self-induced transparency effect is discussed. Some problems arising from the inconsistent use of relativity are pointed out.

Wireless Energy Harvesting by Direct Voltage Multiplication on Lateral Waves From a Suspended Dielectric Layer

This paper explores the feasibility of wireless energy harvesting by direct voltage multiplication on lateral waves. Whilst free space is undoubtedly a known medium for wireless energy harvesting, space waves are too attenuated to support realistic transmission of wireless energy. A layer of thin stratified dielectric material suspended in mid-air can form a substantially less attenuated pathway, which efficiently supports propagation of wireless energy in the form of lateral waves. The conductivity of the suspended dielectric layer does not appear to be a critical factor rendering propagation of lateral waves impossible. In this paper, a mathematical model has been developed to simulate wireless energy harvesting over a suspended layer of stratified dielectric material. The model has been experimentally verified with the help of a novel open-ended voltage multiplier designed to harvest energy from ambient electromagnetic fields.

A statistical assessment of ambient electromagnetic field using body-worn multiaxial sensors

The electromagnetic field exposure of the population due to wireless communications originates from both down-link and up-link emissions. Although the main contribution comes generally from the latter (e.g., higher by three to five orders of magnitude for the 2G), the former must be considered as well, because they are continual, and as contributions can be competitive for some cases (e.g., in femtocells). Sensor and exposimeter networks (NW) can be deployed by the operators themselves (to enrich feedback information from their own NW) or by independent external stakeholders such as regulatory agencies or local authorities. When sensors are directly worn by a user, body proximity effects – notably the masking effect – can introduce significant errors in the ambient field measurement. A methodology of the statistical assessment of this harmful effect is proposed in this article. It is mainly based on electromagnetic simulations (and partly on measurements) of a triaxial sensor – composed of three orthogonal wideband probes devoted to the evaluation of the field components – placed at different positions of a set of whole body phantoms. The main original contribution of the proposed approach is that both the isolated sensor calibration procedure and the assessment of the measurement errors are based on statistical analyses accounting for the propagation environment. The quantitative results are obtained using statistical channel models for polarimetric and non-polarimetric measurements in various propagation scenarios. Some quantitative results examples are presented. Eventually, preliminary corrections schemes are proposed. L'exposition de la population aux ondes électromagnétiques dues aux communications radio émane tant des émissions descendantes que montantes. Bien que la contribution dominante provienne généralement de ces dernières (supérieures de trois à cinq ordres de grandeur pour la 2G par exemple), les premières doivent également être prises en compte, notamment parce qu'elles sont permanentes, mais aussi parce que les deux contributions peuvent être compétitives dans certains cas (par exemple dans les femtocells ). Des réseaux de capteurs et d'exposimètres peuvent être déployés par les opérateurs eux-mêmes (leur permettant d'enrichir les informations remontées par leur propre réseau) ou par des acteurs extérieurs indépendants, tels que des organismes de contrôle réglementaire ou des collectivités locales. Si les capteurs sont directement portés par l'utilisateur, les effets de proximité du corps – notamment l'effet de masquage – peuvent introduire des erreurs très significatives dans la mesure du champ ambiant. Nous proposons dans cet article une méthodologie d'estimation statistique de cet effet néfaste. L'approche est majoritairement fondée sur des simulations électromagnétiques (et partiellement sur des mesures) d'un capteur triaxial – constitué de trois sondes large bande placées orthogonalement dédiées à la mesure des composantes du champ – placé à différentes positions de fantômes « corps entier ». L'originalité principale de cette contribution est qu'elle repose sur des analyses statistiques prenant en compte les conditions de propagation, que ce soit dans la procédure de calibration du capteur isolé ou dans l'évaluation des erreurs de mesure. Les résultats quantitatifs sont obtenus à partir de modèles statistiques de canaux, pour des mesures polarimétriques ou non, pour différents scénarios de propagation. Quelques résultats quantitatifs sont présentés. Pour terminer, des méthodes envisageables de correction encore à l'étude sont présentées.

Temporal Homogenization of Linear ODEs, with Applications to Parametric Super-Resonance and Energy Harvest

We consider the temporal homogenization of linear ODEs of the form $\dot{x}=Ax+\epsilon P(t)x+f(t)$, where $P(t)$ is periodic and $\epsilon$ is small. Using a 2-scale expansion approach, we obtain the long-time approximation $x(t)\approx \exp(At) \left( \Omega(t)+\int_0^t \exp(-A \tau) f(\tau) \, d\tau \right)$, where $\Omega$ solves the cell problem $\dot{\Omega}=\epsilon B \Omega + \epsilon F(t)$ with an effective matrix $B$ and an explicitly-known $F(t)$. We provide necessary and sufficient condition for the accuracy of the approximation (over a $\mathcal{O}(\epsilon^{-1})$ time-scale), and show how $B$ can be computed (at a cost independent of $\epsilon$). As a direct application, we investigate the possibility of using RLC circuits to harvest the energy contained in small scale oscillations of ambient electromagnetic fields (such as Schumann resonances). Although a RLC circuit parametrically coupled to the field may achieve such energy extraction via parametric resonance, its resistance $R$ needs to be smaller than a threshold $\kappa$ proportional to the fluctuations of the field, thereby limiting practical applications. We show that if $n$ RLC circuits are appropriately coupled via mutual capacitances or inductances, then energy extraction can be achieved when the resistance of each circuit is smaller than $n\kappa$. Hence, if the resistance of each circuit has a non-zero fixed value, energy extraction can be made possible through the coupling of a sufficiently large number $n$ of circuits ($n\approx 1000$ for the first mode of Schumann resonances and contemporary values of capacitances, inductances and resistances). The theory is also applied to the control of the oscillation amplitude of a (damped) oscillator.

Progress Toward a Deployable SQUID-Based Ultra-Low Field MRI System for Anatomical Imaging

Magnetic resonance imaging (MRI) is the best method for non-invasive imaging of soft tissue anatomy, saving countless lives each year. But conventional MRI relies on very high fixed strength magnetic fields, ≥ 1.5 T, with parts-permillion homogeneity, requiring large and expensive magnets. This is because in conventional Faraday-coil based systems the signal scales approximately with the square of the magnetic field. Recent demonstrations have shown that MRI can be performed at much lower magnetic fields (~100 μT, the ULF regime). Through the use of pulsed prepolarization at magnetic fields from ~10-100 mT and SQUID detection during readout (proton Larmor frequencies on the order of a few kHz), some of the signal loss can be mitigated. Our group and others have shown promising applications of ULF MRI of human anatomy including the brain, enhanced contrast between tissues, and imaging in the presence of (and even through) metal. Although much of the required core technology has been demonstrated, ULF MRI systems still suffer from long imaging times, relatively poor quality images, and remain confined to the R&D laboratory due to the strict requirements for a low noise environment isolated from almost all ambient electromagnetic fields. Our goal in the work presented here is to move ULF MRI from a proof-of-concept in our laboratory to a functional prototype that will exploit the inherent advantages of the approach, and enable increased accessibility. Here we present results from a seven-channel SQUID-based system that achieves pre-polarization field of 100 mT over a 200 cm3 volume, is powered with all magnetic field generation from standard MRI amplifier technology, and uses off the shelf data acquisition. As our ultimate aim is unshielded operation, we also demonstrated a seven-channel system that performs ULF MRI outside of heavy magnetically-shielded enclosure. In this paper we present preliminary images and compare them to a model, and characterize the present and expected performance of this system.

Optical Trapping of Nanoparticles

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec, which has serious implications for biological matter. A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure. The double-nanohole structure has been shown to give a strong local field enhancement. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres and 3.4 nm hydrodynamic radius bovine serum albumin proteins. In this work, the experimental configuration used for nanoparticle trapping is outlined. First, we detail the assembly of the trapping setup which is based on a Thorlabs Optical Tweezer Kit. Next, we explain the nanofabrication procedure of the double-nanohole in a metal film, the fabrication of the microfluidic chamber and the sample preparation. Finally, we detail the data acquisition procedure and provide typical results for trapping 20 nm polystyrene nanospheres.

Optical Trapping of Nanoparticles

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam1. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles1. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec1, which has serious implications for biological matter2,3. A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime4. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure. The double-nanohole structure has been shown to give a strong local field enhancement5,6. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres7 and 3.4 nm hydrodynamic radius bovine serum albumin proteins8. In this work, the experimental configuration used for nanoparticle trapping is outlined. First, we detail the assembly of the trapping setup which is based on a Thorlabs Optical Tweezer Kit. Next, we explain the nanofabrication procedure of the double-nanohole in a metal film, the fabrication of the microfluidic chamber and the sample preparation. Finally, we detail the data acquisition procedure and provide typical results for trapping 20 nm polystyrene nanospheres.