Microscale and nanoscale robots, frequently referred to as future cargo systems for targeted drug delivery, can effectively convert magnetic energy into locomotion. However, navigating and imaging them within a complex colloidal vascular system at a clinical scale is exigent. Hence, a more precise and enhanced hybrid control navigation and imaging system is necessary. Magnetic particle imaging (MPI) has been successfully applied to visualize the ensemble of superparamagnetic nanoparticles (MNPs) with high temporal sensitivity. MPI uses the concept of field-free point (FFP) mechanism in the principal magnetic field. The gradient magnetic field (|∇B|) of MPI scanners can generate sufficient magnetic force in MNPs; hence, it has been recently used to navigate nanosized particles and micron-sized swimmers. In this article, we present a simulation analysis of the optimized navigation of an ensemble of microsized polymer MNP-based drug carriers in blood vessels. Initially, an ideal two-dimensional FFP case is employed for the basic optimization of the FFP position to achieve efficient navigation. Thereafter, a nine-coil electromagnetic actuation simulation system is developed to generate and manipulate the FFP position and |∇B|. Under certain vessel and fluid conditions, the particle trajectories of different ferromagnetic polymer ratios and |∇B| were compared to optimize the FFP position.

The potential of laser-driven ion beam applications is limited by high quality requirements. The excellent “point-source” characteristics of the laser accelerated proton beam in a broad energy range were found by using proton radiographs of a mesh. The “virtual source” of protons, the point where the proton trajectories are converging and form a waist, gradually decreases and moves asymptotically to the target with increasing particles' energy. Computer simulations confirmed that the beam profile at the center is fully conserved, the virtual source of higher energy protons gradually moves closer to the target, and if the particle energy is further increased, the virtual source will be located on the target front surface (for portions above 13 MeV, in this case) with a size comparable to the laser spot size. The laser ponderomotive force pushes the electrons deep into the target creating a bipolar charge structure, i.e., an electron cavity and spike which produces strong accelerating field, realizing a point-size source of accelerated protons. This behavior has not previously been predicted. These results contribute to the development of next generation laser-accelerators suitable for many applications.

A new design of an ion mass spectrometer for the laser-plasma particle diagnostic, which is capable to detect simultaneously also neutral particles, is described. The particles are detected with micro-channel-plate detector operating in a gated mode. This allows us to separate x-rays and energetic electrons from other stray plasma emissions, e.g., neutral particles, which hit the detector in the same place. The ion energies are measured with the spectrometer in energy intervals corresponding to their time-of-flight within the gating window. The latter also defines the energy interval of neutrals recorded with the same time-of-flight. The spectrum of neutral particles can be reconstructed by subsequently collecting different parts of the spectrum while applying different delays on the gate pulse. That separation-in-time technique (time-of-flight mass spectrometry) in combination with the spatially separating mass analyzer (ion mass spectrometer) is used for the neutral particles spectroscopy.

Microrobots driven by multiple external power sources have emerged as promising tools for targeted drug and stem cell delivery in tissue regeneration. However, navigating and imaging these devices within a complex colloidal vascular system at a clinical scale is challenging. Ultrasonic actuators have gained interest in the field of non-contact manipulation of micromachines due to their label-free biocompatible nature and safe operation history. This research presents experimentally validated simulation results of ultrasonic actuation using a novel ultrasonic transducer array with a hemispherical arrangement that generates active traveling waves with phase modulation. Blood flow is used as a carrier force while the direction and path are controlled by blocking undesirable paths using a highly focused acoustic field. In the experiments, the microrobot cluster was able to follow a predefined trajectory and reach the target. The microrobot size, maximum radiation pressure, and focus position were optimized for certain blood flow conditions. The outcomes suggest that this acoustic manipulation module has potential applications in targeted tumor therapy.

The interaction of Circularly Polarized Electro-Magnetic (CPEM) waves with a 4-component relativistic quantum plasma is studied. The plasma constituents are: relativistic-degenerate electrons and positrons, dynamic degenerate ions, and Thomas-Fermi distributed electrons in the background. We have employed the Klein-Gordon equations for the electrons as well as for the positrons, while the ions are represented by the Schrödinger equation. The Maxwell and Poisson equations are used for electromagnetic waves. Three modes are observed: one of the modes is associated with the electron acoustic wave, a second mode at frequencies greater than the electron acoustic wave mode could be associated with the positrons, and the third one at the lowest frequencies could be associated with the ions. Furthermore, Stimulated Raman Scattering (SRS), Modulational, and Stimulated Brillouin Scattering (SBS) instabilities are studied. It is observed that the growth rates of both the SRS and SBS instabilities decrease with increase in the quantum parameter of the plasma. It is also observed that the scattering spectra in both the SRS and SBS get restricted to very small wavenumber regions. It is shown that for low amplitude CPEM wave interaction with the quantum plasma, the positron concentration has no effect on the SRS and SBS spectra. In the case of large amplitude CPEM wave interaction, however, one observes spectral changes with varying positron concentrations. An increase in the positron concentration also enhances the scattering instability growth rates. Moreover, the growth rate first increases and then decreases with increasing intensity of the CPEM wave, indicating an optimum value of the CPEM wave intensity for the growth of these scattering instabilities. The modulational instability also shows dependence on the quantum parameter as well as on the positron concentration.