Time-division multiplexing for cable reduction in ultrasound imaging catheters

In ultrasound imaging catheter applications, gathering the data from multi-element transducer arrays is difficult as there is a restriction on cable count due to the diameter of the catheter. In such applications, CMUT-on-CMOS technology allows for 2D arrays with many elements to be designed and bonded directly onto CMOS circuitry. This allows for complex electronics to be placed at the tip of the catheter which leads to the possibility to include electronic multiplexing techniques to greatly reduce the cable count required for a large element array. Current approaches to cable reduction tend to rely on area and power hungry circuits to function, making them unsuitable for use in catheters. Furthermore the length requirement for catheters and lack of power available to on-chip cable drivers leads to limited signal strength at the receiver end. In this paper an alternative approach using Analogue Time Division Multiplexing (TDM) is presented, which addresses the cable restrictions of the catheter and, using a novel digital demultiplexing technique, allows for a reduction in the number of analogue signal processing stages required

Direct Digital Demultiplexing of Analog TDM Signals for Cable Reduction in Ultrasound Imaging Catheters.

In real-time catheter based 3D ultrasound imaging applications, gathering data from the transducer arrays is difficult as there is a restriction on cable count due to the diameter of the catheter. Although area and power hungry multiplexing circuits integrated at the catheter tip are used in some applications, these are unsuitable for use in small sized catheters for applications like intracardiac imaging. Furthermore, the length requirement for catheters and limited power available to on-chip cable drivers leads to limited signal strength at the receiver end. In this paper an alternative approach using Analog Time Division Multiplexing (TDM) is presented which addresses the cable restrictions of ultrasound catheters. A novel digital demultiplexing technique is also described which allows for a reduction in the number of analog signal processing stages required. The TDM and digital demultiplexing schemes are demonstrated for an intracardiac imaging system that would operate in the 4 MHz to 11 MHz range. A TDM integrated circuit (IC) with 8:1 multiplexer is interfaced with a fast ADC through a micro-coaxial catheter cable bundle, and processed with an FPGA RTL simulation. Input signals to the TDM IC are recovered with -40 dB crosstalk between channels on the same micro-coax, showing the feasibility of this system for ultrasound imaging applications

Front-end electronics for cable reduction in Intracardiac Echocardiography (ICE) catheters

3-D imaging ICE catheters with large element counts present design challenges in achieving simultaneous data readout from all elements while significantly reducing cable count for a small catheter diameter. Current approaches such as microbeamformer techniques tend to rely on area and power hungry circuits, making them undesirable for ICE catheters. In this paper, a system which uses are an efficient real-time programmable on-chip transmit (TX) beamformer circuitry to reduce the cable count on the TX side and analog 8/1 Time Division Multiplexing (TDM) with Direct Digital Demodulation (DDD) to reduce the cable count on the receive (RX) side is presented

Single-Chip Reduced-Wire CMUT-on-CMOS System for Intracardiac Echocardiography

CMUT-on-CMOS integration is particularly suitable for catheter based ultrasound imaging applications, where electronics integration enables multiplexing capabilities to reduce the number of electrical connections leading to smaller catheter cable profiles. Here, a single-chip CMUT-on-CMOS system for intracardiac echocardiography (ICE) is presented. In this system, a 64 element 1-D CMUT array is fabricated over an application specific integrated circuit (ASIC) that features a programmable transmit beamformer with high voltage (HV) pulsers and receive circuits using 8:1 time division multiplexing (TDM). Integration of pitch matched 64 channel front-end circuits with CMUT arrays in a single-chip configuration allows for implementation of catheter probes with miniaturization, reduced number of cables, and better mechanical flexibility. The ASIC is implemented in 60 V 0.18 μm HV process. It occupies 2.6×11 mm 2 which can fit in the catheter size of 9F, and reduces the number of wires from more than 64 to 22. This system is used for B-mode imaging of imaging phantoms and its potential application for 2D CMUT-on-CMOS arrays is discussed

Recent Advances, Development, and Impact of Using Phase Change Materials as Thermal Energy Storage in Different Solar Energy Systems: A Review

The efficient utilization of solar energy technology is significantly enhanced by the application of energy storage, which plays an essential role. Nowadays, a wide variety of applications deal with energy storage. Due to the intermittent nature of solar radiation, phase change materials are excellent options for use in several types of solar energy systems. This overview of the relevant literature thoroughly discusses the applications of phase change materials, including solar collectors, solar stills, solar ponds, solar air heaters, and solar chimneys. Despite the complexity of their availability and high costs, phase change materials are utilized in the majority of solar energy techniques because of the considerable technical improvements they provide. While numerous studies have investigated the progress of phase change materials used in solar energy applications such as photovoltaic systems, it is vital to understand the conceptual knowledge of employing phase change materials in various types of solar thermal energy systems. Investigations into the use of phase change materials in solar applications for the purpose of storing thermal energy are still being carried out to upgrade the overall performance. This paper briefly reviews recently published studies between 2016 and 2023 that utilized phase change materials as thermal energy storage in different solar energy systems by collecting more than 74 examples from the open literature. This study focuses on demonstrating the maturity of phase change materials and their integration into solar energy applications. Based on the findings, proposals for new research projects are made

A Review of Recent Improvements, Developments, and Effects of Using Phase-Change Materials in Buildings to Store Thermal Energy

When it comes to guaranteeing appropriate performance for buildings in terms of energy efficiency, the building envelope is a crucial component that must be presented. When a substance goes through a phase transition and either gives out or absorbs an amount of energy to provide useful heat or cooling, it is called a phase-change material, or PCM for short. Transitions often take place between the matter’s solid and liquid states. Buildings use PCMs for a variety of purposes, including thermal comfort, energy conservation, managing the temperature of building materials, reducing cooling/heating loads, efficiency, and thermal load shifting. Improved solutions are applied using new method and approach investigations. Undoubtedly, researching and applying PCM use in building applications can help create buildings that are more energy-efficient and environmentally friendly, while also increasing thermal comfort and consuming less energy. It provides a possible answer to the problems posed by climate change, rising energy demand in the built environment, and energy use optimisation. However, it is true that no particular research has yet been conducted to thoroughly analyse the linked PCM applications in the building industry. Thus, the principal tactics are addressed in this paper to determine current and efficient methods for employing PCMs in buildings to store thermal energy. By gathering around 50 instances from the open literature, this study conducts a thorough assessment of the up-to-date studies between 2016 and 2023 that used PCMs as thermal energy storage in building applications. As a result, this review aims to critically evaluate the PCM integration in buildings for thermal energy storage, identify a number of issues that require more research, and draw some important conclusions from the body of literature. Specifically, the building envelope roof and external wall uses of PCMs are highlighted in this research. Applications, general and desired characteristics, and PCM types and their thermal behaviour are described. In comparison to a traditional heat storage tank that simply contains water, this review indicates that a water storage tank containing 15% PCM improves heat storage by 70%. Also, less than 7 °C of internal air temperature was reduced by the PCMs in the walls, which avoided summer warming. Finally, using PCM for space cooling resulted in substantial energy savings across the various seasons

Single-Chip Reduced-Wire Active Catheter System with Programmable Transmit Beamforming and Receive Time-Division Multiplexing for Intracardiac Echocardiography

Intracardiac echocardiography (ICE) provides real-time ultrasound imaging of the heart anatomy from inside, guiding interventions like valve repair, closure of atrial septal defects (ASD) and catheter-based ablation to treat atrial fibrillation. With its better image quality and ease of use, ICE is becoming the preferred imaging modality over transesophageal echography (TEE) for structural heart interventions. The existing commercial ICE catheters, however, offer a limited 2-D or 3-D field of view despite catheters utilizing large number of wires. In these catheters, each element in the ICE array is connected to the backend data-acquisition channel with a separate wire, which is a critical barrier for improving image quality and widening the field of view. In order to use ICE catheters under MRI instead of the ionizing X-ray radiation-based angiography, the number of interconnect wires in the catheter should be minimized to reduce RF-induced heating. Furthermore, reducing the number of wires improves the flexibility and lowers the cost of the single-use ICE catheters

A Review of Recent Improvements, Developments, Effects, and Challenges on Using Phase-Change Materials in Concrete for Thermal Energy Storage and Release

Most concrete employs organic phase change materials (PCMs), although there are different types available for more specialised use. Organic PCMs are the material of choice for concrete due to their greater heat of fusion and lower cost in comparison to other PCMs. Phase transition materials are an example of latent heat storage materials (LHSMs) that may store or release thermal energy at certain temperatures. A phase transition occurs when a solid material changes from a solid state to a liquid state and back again when heat is added or removed. It is common knowledge that adding anything to concrete, including PCMs, will affect its performance. The goal of this review is to detail the ways in which PCMs affect certain concrete features. This overview also looks into the current challenges connected with employing PCMs in concrete. The review demonstrates a number of important findings along with the possible benefits that may pave the way for more research and broader applications of PCMs in construction. More importantly, it has been elucidated that the optimum PCM integrated percentage of 40% has doubled the quantity of thermal energy stored and released in concrete. Compared to conventional concrete, the macro-encapsulated PCMs showed thermal dependability, chemical compatibility, and thermal stability due to delaying temperature peaks. Furthermore, the maximum indoor temperature decreases by 1.85 °C and 3.76 °C in the test room due to the addition of 15% and 30% PCM composite, respectively. Last but not least, incorporating microencapsulated PCM has shown a positive effect on preventing freeze-thaw damage to concrete roads

Recent Advances on The Applications of Phase Change Materials in Cold Thermal Energy Storage: A Critical Review

Cold thermal energy storage (CTES) based on phase change materials (PCMs) has shown great promise in numerous energy-related applications. Due to its high energy storage density, CTES is able to balance the existing energy supply and demand imbalance. Given the rapidly growing demand for cold energy, the storage of hot and cold energy is emerging as a particularly attractive option. The main purpose of this study is to provide a comprehensive overview of the current research progress on the utilisation of PCMs in CTES. The greatest difficulties associated with using PCMs for CTES are also examined in this overview. In this regard, a critical evaluation of experimental and numerical studies of the heat transfer properties of various fundamental fluids using PCMs is conducted. Specifically, several aspects that affect the thermal conductivity of PCMs are investigated. These factors include nanoparticle-rich PCM, a form of encapsulated PCM, solids volume percentage, and particle size. Discussions focus on observations and conclusions are drawn from conducted studies on PCMs used in CTES. Based on the findings of this study, a set of plausible recommendations are made for future research initiatives

Thermal Management of the Melting Process in a Latent Heat Triplex Tube Storage System Using Different Configurations of Frustum Tubes

In this study, the energy charging mechanism is mathematically modeled to determine the impact of design modifications on the thermofluidic behavior of a phase change material (PCM) filled in a triplex tube containment geometry. The surface area of the middle tube, where the PCM is placed, is supported by single or multi-internal frustum tubes in vertical triplex tubes to increase the performance of the heating and cooling of the system. In addition to the ordinary straight triplex tubes, three more scenarios are considered: (1) changing the middle tube to the frustum tube, (2) changing the inner tube to the frustum tube, and (3) changing both the internal and central tubes to the frustum tubes. The impact of adopting the tube designs and gap width were studied. The outcomes reveal that the heat storage rates are increased for all frustum tube systems compared to the straight tube system. According to the results, the case of a gap width of 5 mm is the optimal one among the studied cases in terms of the melting time and the heat storage rate. Employing the frustum tube configuration with a 5-mm gap width would save the melting time by 25.6% and increase the rate of heat storage by 32.8% compared to the base case of straight tubes