This paper investigates the design and modelling of an integrated device for acoustic resonance spectroscopy (ARS). Miniaturisation of such platforms can be achieved using MEMS technology thereby enabling scaling of device dimensions to investigate smaller specimens while simultaneously operating at higher frequencies. We propose an integrated device where the transducers are mounted in close proximity with the specimen to be analysed (e.g. by integrating ultrasound transducers within a microfluidic channel). A finite element (FE) model and a simplified analytical model have been constructed to predict the acoustic response of a sample embedded in such a device configuration. A FE simulation is performed in COMSOL by embedding the piezoelectric transducers in representative fluid media. Resonant frequencies associated with the measurement can be extracted from this data. The response of various media modelled through FEA matches with analytical predictions for a range of biological media. A variety of biological media may be identified by using the measured resonant frequencies as a signature of relevant physical characteristics. The paper establishes the modelling basis of an integrated acoustic resonant spectrometer that is then applied to examine the impact of geometrical scaling on system resolution.

This paper reports, for the first time, a method for characterizing liquid samples in a microfluidic device using continuous wave broadband ultrasound spectroscopy. An analytical model to predict the transmission response of the device is developed along with an experimental setup which is constructed to validate the model over a set of length scales. Experiments are then conducted to characterize various liquid samples, including glucose-water solutions, contained within the milli-cavity devices using contact type ultrasound transducers (with center frequency 15 MHz). An algorithm to process the measured response to calculate the speed of sound in the liquid channel by filtering the total response with those of the intermediate layers is developed. The models and experimental results show that is possible to utilize this relatively simple and non-contact ultrasound interrogation technique for quantifying the concentration of chemical analytes in liquid samples.

Persistence of the ductus arteriosus (DA) after birth leads to the congenital heart disease known as patent ductus arteriosus (PDA). The objective of this study is to develop an evaluation protocol and to propose a new and innovative intraductal design for a PDA occluder in order to conform to the varied morphology of the DA and to overcome the problems associated with devices relying on the anchorage mechanism. The new design, an assembly of 36 planar thermally treated Nitinol wires called Novel Device 36 (ND36), is in the shape of a frustum of a cone with a larger diameter of 12 mm, smaller diameter of 6 mm, and length of 11 mm. In-vitro biomimetic evaluations, namely, hemolysis tests and platelet adhesion studies, were conducted to ascertain the biocompatibility of the thermally treated Nitinol wires. These tests were also conducted on two different dimensions of Dacron fibers, which were to be sutured onto the device to induce thrombogenesis while in the duct, thereby facilitating better occlusion. Flow dynamics tests, which help simulate the dynamic conditions prevalent in the duct, were carried out on the ND36 and a commercially used PDA occlusion device. An analysis of the scanning electronic microscopy images showed no platelet adhesion on the Nitinol wires. The tested wires also showed nearly 0% hemolysis. Dacron fibers 0.2 mm thick and having an area density of 77 GSM proved to be best suited. Comparative analysis carried out with the commercially available Amplatzer duct occluder during the flow dynamics tests showed that the ND36 was capable of effectively occluding the duct as well as remaining stable under the dynamic conditions encountered in the duct. The ND36 has the potential to efficiently serve as a simplistic and cost effective alternative for PDA occlusion.

Wafer bonding is a process in Micro Electro Mechanical Systems (MEMS) and microelectronics fabrication, allowing for integrating different materials and devices into a unified structure. Fusion bonding, a specific type of wafer bonding, offers several advantages, including high bonding strength, excellent thermal stability, and compatibility with various materials. This technique directly joins two substrates without requiring intermediate layers, making it a preferred choice in many applications. In the proposed work, a comparison study of the various surface activation techniques on different glass samples to modify the surface properties for better bonding strength with low bonding temperatures. The surface-activated samples are characterized using Raman Spectroscopy to identify the best suitable treatment for fusion bonding. Further, fused silica - fused silica samples are directly bonded at 400 °C temperature after surface activation. The bond strength of these bonded glass samples is measured using Die shear tester.