Publications by authors named "Youhan Sunny"
The purpose of this work was to investigate the ability of bubbles entrapped within echogenic liposomes (ELIP) to serve as foci for cavitational events that would cause leakage in neighboring non-echogenic liposomes (NELIP). Previous studies have shown that entrapping bubbles into liposomes increases ultrasound-mediated leakage of hydrophilic components at ultrasound settings known to induce inertial cavitation, specifically 20kHz and 2.2W/cm.
View Article and Find Full Text PDFThe purpose of this work was to investigate whether low-frequency, low-intensity (20 kHz, <100 mW/cm(2), spatial-peak, temporal-peak intensity) ultrasound, delivered with a lightweight (<100 g), tether-free, fully wearable, battery-powered applicator, is capable of reducing inflammation in a mouse model of rheumatoid arthritis. The therapeutic, acute, anti-inflammatory effect was estimated from the relative swelling induced in mice hindlimb paws. In an independent, indirect approach, the inflammation was bio-imaged by measuring glycolytic activity with near-infrared labeled 2-deoxyglucose.
View Article and Find Full Text PDFIsolated neonatal rat ventricular cardiomyocytes were used to study the influence of ultrasound on the chronotropic response in a tissue culture model. The beat frequency of the cells, varying from 40 to 90 beats/min, was measured based upon the translocation of the nuclear membrane captured by a high-speed camera. Ultrasound pulses (frequency = 2.
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- - The study investigated the effectiveness of low-frequency (<100 kHz), low-intensity (<100 mW/cm²) ultrasound as a treatment for venous stasis ulcers, which affect around 500,000 patients each year and are costly to treat.
- - Twenty participants received either 20 or 100 kHz ultrasound treatments over several sessions, with results showing that those treated with 20 kHz for 15 minutes had significantly faster wound healing and all fully healed by the fourth treatment.
- - In vitro experiments demonstrated that 20 kHz ultrasound increased cellular metabolism by 32% and cell proliferation by 40%, suggesting that this ultrasound treatment may effectively aid in healing venous ulcers.
Article Synopsis
- The study investigates how changes in the composition of microbubble shells, specifically the amount and weight of polyethylene glycol (PEG), affect their resonance frequency when ultrasound waves pass through them.
- The experiments show that at low PEG concentrations (0.01), the molecular weight has little effect on resonance frequency; however, at higher concentrations (0.075), the resonance frequency decreases significantly with increasing PEG molecular weight.
- Data analysis using the Sarkar bubble dynamics model reveals a consistent pattern with theoretical predictions regarding the elastic modulus, confirming its constancy in the mushroom regime and a decrease in the brush regime as molecular weight increases.
This paper focuses on the development of a finite-element model and subsequent stationary analysis performed to optimize individual flexural piezoelectric elements for operation in the frequency range of 20-100kHz. These elements form the basic building blocks of a viable, un-tethered, and portable ultrasound applicator that can produce intensities on the order of 100mW/cm(2) spatial-peak temporal-peak (I(SPTP)) with minimum (on the order of 15V) excitation voltage. The ultrasound applicator can be constructed with different numbers of individual transducer elements and different geometries such that its footprint or active area is adjustable.
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- This paper focuses on optimizing lightweight, battery-operated ultrasound transducers for biomedical use, targeting frequencies of 20-100kHz.
- The aim is to create a wearable ultrasound applicator that operates on low excitation voltages (10-25V) while delivering sufficient acoustic pressure (approximately 55kPa or 100mW/cm²) for therapeutic applications like chronic wound management and drug delivery.
- Early prototypes were designed using complex impedance analysis and are powered by portable lithium polymer batteries, enabling features like adjustable duty cycles and continuous or pulsed operation.