Browsing by Author "Bonakdar, Mohammad"
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- Devices, systems, and methods for real-time monitoring of electrophysical effects during tissue treatment(United States Patent and Trademark Office, 2020-06-30)Provided herein are devices, systems, and methods for monitoring lesion or treated area in a tissue during focal ablation or cell membrane disruption therapy. Provided herein are embodiments of an electrical conductivity sensor having an impedance sensor, where the impedance sensor can be configured to measure a low-frequency and a high-frequency impedance and a substrate, where the impedance sensor is coupled to the substrate. The substrate can be flexible. In embodiments, the impedance sensor can contain two or more electrical conductors. The electrical conductors can be in a bipolar configuration. The electrical conductors can be in a tetrapolar configuration. In embodiments, the electrical conductivity sensor can have two impedance sensors that can be coupled to the substrate such that they are orthogonal to each other.
- Effects of internal electrode cooling on irreversible electroporation using a perfused organ modelO’Brien, T. J.; Bonakdar, Mohammad; Bhonsle, Suyashree P.; Neal, Robert E.; Aardema, C.H.; Robertson, John L.; Goldberg, S.N.; Davalos, Rafael V. (Taylor and Francis Ltd, 2018-05-28)Purpose: This study evaluates the effects of active electrode cooling, via internal fluid circulation, on the irreversible electroporation (IRE) lesion, deployed electric current and temperature changes using a perfused porcine liver model. Materials and methods: A bipolar electrode delivered IRE electric pulses with or without activation of internal cooling to nine porcine mechanically perfused livers. Pulse schemes included a constant voltage, and a preconditioned delivery combined with an arc-mitigation algorithm. After treatment, organs were dissected, and treatment zones were stained using triphenyl-tetrazolium chloride (TTC) to demonstrate viability. Results: Thirty-nine treatments were performed with an internally cooled applicator and 21 with a non-cooled applicator. For the constant voltage scenario, the average final electrical current measured was 26.37 and 29.20 A for the cooled and uncooled electrodes respectively (p≤.001). The average final temperature measured was 33.01 and 42.43 °C for the cooled and uncooled electrodes respectively (p≤.0001). The average measured ablations (fixed lesion) were 3.88-by-2.08 cm and 3.86-by-2.12 cm for the cooled and uncooled electrode respectively (p≤.2495, p≤.7507). Similarly, the preconditioned/arc-mitigation scenario yielded an average final electrical current measurement of a 41.07 and 47.20 A for the cooled and uncooled electrodes respectively (p≤.0001). The average final temperature measured was 34.93 and 44.90 °C for the cooled and uncooled electrodes respectively (p≤.0001). The average measured ablations (fixed lesion) were 3.67-by-2.27 cm and 3.58-by-2.09 cm for the cooled and uncooled applicators ((p≤.7906; p≤.5595)). Conclusions: The internally-cooled bipolar applicator offers advantages that could improve clinical outcomes. Thermally mitigating internal perfusion technology reduced tissue temperatures and electric current while maintaining similar lesion sizes.
- Microdevices for Investigating Pulsed Electric Fields-Mediated Therapies at Cellular and Tissue LevelBonakdar, Mohammad (Virginia Tech, 2016-06-29)Recent attempts to investigate living systems from a biophysical point of view has opened new windows for development of new diagnostic methods and therapies. Pulsed electric fields (PEFs) are a new class of therapies that take advantage of biophysical properties and have proven to be effective in drug delivery and treating several disorders including tumors. While animal models are commonly being used for development of new therapies, the high cost and complexity of these models along with the difficulties to control the electric field in the animal tissue are some of the obstacles toward the development of PEFs-based therapies. Microengineered models of organs or Organs-on-Chip have been recently introduced to overcome the hurdles of animal models and provide a flexible and cost-effective platform for early investigation of a variety of new therapies. In this study microfluidic platforms with integrated micro-sensors were designed, fabricated and employed to study the consequences of PEFs at the cellular level. These platforms were specifically used to study the effects of PEFs on the permeabilization of the blood-brain barrier for enhanced drug delivery to the brain. Different techniques such as fluorescent microscopy and electrical impedance spectroscopy were used to monitor the response of the cell monolayers under investigation. Irreversible electroporation is a new focal ablation therapy based on PEFs that has enabled ablation of tumors in a non-thermal, minimally invasive procedure. Despite promising achievements and treatment of more than 5500 human patients by this technique, real-time monitoring of the treatment progress in terms of the size of the ablated region is still needed. To address that necessity we have developed micro-sensor arrays that can be implemented on the ablation probe and give real-time feedback about the size of the ablated region by measuring the electrical impedance spectrum of the tissue.