Taehoon Kim
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14 records found
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IN [1], there is a mistake in the timing diagram shown in Fig. 6. Switches S 1-S 4 are skipping some of the samples and the rate at which they are operating implies a TDM rate of 10 MHz, whereas (as described in [1]) this should be 20 MHz. In the updated Fig. 6, S 1-S 4 have been updated and a minor change has been made to the timing shown for switches Q1 and Q2, such that the correct TDM rate is indicated and no sample provided to the S/H stage via N1-N4 is skipped in the diagram. (Figure presented).
Conventional strategies for the management of acute pain have significant limitations. Pharmaceutical approaches carry risks for addiction and misuse. Standard implantable devices require secondary surgeries for removal and physical tethers to external systems for power and control. Recent work on bioresorbable electrical stimulators overcomes certain of these drawbacks, but existing versions still depend on transcutaneous leads. Here, we introduce a platform that employs thermal mechanisms for nerve block to bypass some of these limitations. The system integrates both a Joule heating element and a resistive temperature sensor in a soft cuff structure as a nerve interface, in which most of the materials are bioresorbable over a clinically relevant timeframe. This design enables precise control of nerve temperature within a safe range (≤45°C) for effective nerve block through a feedback-guided strategy that continuously monitors temperature and adjusts current in real time. Options for wireless power delivery eliminate the need for external interfaces. Small animal model studies confirm the reversible and non-invasive operation of this system. The results demonstrate effective suppression of compound nerve action potentials in response to thermal stimulation, with recovery of nerve conduction upon cooling. These findings highlight the potential of this platform as a safe and effective solution to acute pain management.
Over the past decades, ultrasound imaging has made considerable progress based on the advancement of imaging systems as well as transducer technology. With the need for advanced transducer arrays with complex designs and technical requirements, there is also a need for suitable tools to characterize such transducers. However, despite the importance of acoustic characterization to assess the performance of novel transducer arrays, the characterization process of highly complex transducers might involve various manual steps, which are laborious, time-consuming, and subject to errors. These factors can hinder the full characterization of a prototype transducer, leading to an under-representation or inadequate evaluation. To come to an extensive, high-quality evaluation of a prototype transducer, the acoustic characterization of each transducer element is indispensable in both transmit and receive operations. In this paper, we propose a pipeline to automatically perform the acoustic characterization of a matrix transducer using a research imaging system. The performance of the pipeline is tested on a prototype matrix transducer consisting of 960 elements. The results show that the proposed pipeline is capable of performing the complete acoustic characterization of a high-element count transducer in a fast and convenient way.
This paper presents an ultrasound transceiver application-specific integrated circuit (ASIC) directly integrated with an array of 12 × 80 piezoelectric transducer elements to enable next-generation ultrasound probes for 3D carotid artery imaging. The ASIC, implemented in a 0.18 µm high-voltage Bipolar-CMOS-DMOS (HV BCD) process, adopted a programmable switch matrix that allowed selected transducer elements in each row to be connected to a transmit and receive channel of an imaging system. This made the probe operate like an electronically translatable linear array, allowing large-aperture matrix arrays to be interfaced with a manageable number of system channels. This paper presents a second-generation ASIC that employed an improved switch design to minimize clock feedthrough and charge-injection effects of high-voltage metal–oxide–semiconductor field-effect transistors (HV MOSFETs), which in the first-generation ASIC caused parasitic transmis-sions and associated imaging artifacts. The proposed switch controller, implemented with cascaded non-overlapping clock generators, generated control signals with improved timing to mitigate the effects of these non-idealities. Both simulation results and electrical measurements showed a 20 dB reduction of the switching artifacts. In addition, an acoustic pulse-echo measurement successfully demonstrated a 20 dB reduction of imaging artifacts.