Mishal Pokharel

Electrical Impedance Tomography (EIT) is a non-invasive imaging technique that reconstructs interior conductivity from surface voltage measurements. This study benchmarks five finite element–based reconstruction algorithms-Back Projection (BP), Gauss–Newton (GN), Tikhonov Regularization (TR), GREIT, and EIDORS FEM-under controlled hardware conditions. A 16-electrode saline phantom integrated with multiplexers, an amplifier, a function generator, an Arduino Mega, and a DAQ was used, with chicken breast tissue inserted at four unique positions to mimic tumors. Across four excitation signals (10 kHz/1 Vpp, 50 kHz/1 Vpp, 10 kHz/5 Vpp, 50 kHz/5 Vpp), the methods yielded 80 reconstructed images. Performance was evaluated using quantitative metrics including contrast-to-noise ratio (CNR), peak signal-to-noise ratio (PSNR), structural similarity index (SSIM), root mean square error (RMSE), frequency-domain Fast Fourier Transform (FFT), spectrograms, wavelet transform, and spectral temporal energy ratio (STER) to evaluate each method’s performance and robustness. According to our investigation, there are notable variations in image fidelity based on the reconstruction technique and the signal circumstances. Back Projection exhibited artifacts and lower spatial resolution, whereas GREIT and Tikhonov showed the strongest resilience and noise suppression, with EIDORS offering advantages following them. By integrating real hardware signals with phantom experiments, this work offers a practical benchmarking framework and guidance to enhance medical and industrial EIT systems.

Light-actuated microbots have been studied as a viable tool for interacting with micro/nano environments. Considering their applicability to a wide range of biomedical applications, novel designs, fabrication techniques, and control methodologies are being developed. Especially, micro/nanoscale three-dimensional fabrication techniques have opened many possibilities for developing microbots with complex geometries using resins as materials. Here, we developed microbots that can be actuated with tightly focused laser beams to be used in targeted drug delivery, cell poking, and cell characterization studies. These microbots were fabricated in batches using two-photon polymerization (TPP). Each microbot utilizes a deposited metal layer inside its body to manipulate convective microfluidic flows. Additionally, micro-sized end effectors allow them to make measurable physical contact with biological objects. Their expected performance was evaluated using numerical simulations with the use of multiphysics software. Furthermore, laser-induced loading and unloading of micro-sized cargo show their capability for in vitro applications.

The advancement of micro-robotics in recent years has permitted a vast field of active research and application in the biomedical sector. Latest developments in microrobotics point to some ground-breaking work using light for manufacturing as well as actuation. Optical manipulation in three-dimensional space for living biological cells in a minimally invasive manner is crucial for different biomedical applications. This article attempts to provide an overview of the accomplishments and future possibilities of light-powered microbots. An overview of the feasibility of different fabrication techniques and control modalities is compared, along with prospective applications and design considerations of light-powered microbots. A variety of challenges that still prohibit polymeric light-powered microbots from attaining their full potential are pointed out, and viable ways to overcome such challenges are proposed. This study will help future researchers to study and develop the next generation of light-actuated microbots by overcoming the current limitations and challenges in fabrication, control, and design.

Untethered mobile robots at the micro-scale have the ability to improve biomedical research by performing specialized tasks inside complex physiological environments. Light-controlled wireless microbots are becoming the center of interest thanks to their accuracy in navigation and potential to carry out operations in a non-invasive manner inside living environments. The pioneering light-engineered microbots are currently in the early stage of animal trials. There is a long way ahead before they can be employed in humans for therapeutic applications such as targeted drug delivery, cancer cell diagnosis, tissue engineering, etc. The design of light-actuated microbots is one of the challenging parts along with the biocompatibility and precision control for in vivo applications. Recent progress in light-activated microbots has revealed a few innovative design concepts. In this study, we presented a framework on the different aspects with a comparative analysis of potential designs for the next generation of light-controlled microbots. Utilizing numerical simulations of fluid-structure interactions, limiting design elements of the microbots are addressed. We envision that this study will eventually facilitate the integration of robotic applications into the real world owing to the described design considerations.

Achieving a novel drug delivery system needs site-specificity along with dosage control. Many physical, chemical, mechanical, and biological signals are used for developing these systems, out of which light has been used predominantly in the past decade. Light responsive drug delivery systems have tremendous potential, and their exploration is crucial in developing a precise and controlled delivery system. Spatio-temporal and intensity control of light allows better manipulation of drug delivery vehicles than mechanical, chemical, and biological signals. The use of ultraviolet (UV) and near-infrared (NIR) light has helped in upgrading therapeutic functionalities, while the use of up-conversion nanoparticles (UCNPs) has delivered an extension into theranostic tools. Biomaterials incorporated with photosensitizers can readily respond to changes in light and are vital in achieving clinical success via translational research. Further, the inclusion of biological macromolecules for the transportation of drugs, genes, and proteins has seen a broader application of light-controlled systems. The key objective of this review paper is to summarise the evolution of light-activated targeted drug delivery systems and the importance of biomaterials in developing one.