1,720,997 research outputs found
Impedance Measurement Integrated Circuit for Wireless Sensor Readout
No full textThis chip detects the resonant frequency of an inductor-capacitor (LC) wireless sensor by analyzing its impedance characteristics. When wireless coupling occurs between the transmitter (TX) resonator and the receiver (RX) sensor, the impedance of the TX coil varies with the RX sensor’s frequency response. By analyzing the voltage variation across the TX resonator, the TX coil’s impedance can be determined, achieving resonant frequency detection of the RX sensor. Existing portable sensor readout systems using commercial ICs suffer from high complexity and power consumption. To address these issues, an impedance measurement IC is designed. The proposed IC extracts voltage characteristics at both ends of the TX resonator using a single-to-differential converter, mixer, level shifter, and low-pass filter. Therefore, the impedance of the TX coil is derived by dividing the two output DC voltages. Post-layout simulations with varying the TX coil resistance confirm that the measured values match the initial set values. The IC is designed using the TSMC 180nm RF CMOS process.
Reference-Less Time-Division Duplex Transceiver IC for a Renal Denervation System
No full textThis paper presents the first time-division duplex transceiver integrated circuit (IC) for a 5 Fr (1.6 mm), six-electrode renal denervation (RDN) catheter for treating resistant hypertension. The diameter of the resulting RDN catheter, with each IC encapsulated in a platinum electrode, is 37.5% smaller than those of conventional catheters, enabling minimally invasive surgery with reduced complications. The six electrodes sharing only four electrical wires perform packet communication with an external power control unit for independent operation and deliver the designated radio-frequency (RF) energy to the renal artery wall while measuring the local temperature and impedance. The measured 3 sigma inaccuracy of a bipolar junction transistor (BJT)-based on-chip temperature sensor from 65 degrees C to 75 degrees C is +/- 0.5 degrees C after one-point trimming. Two 500-kHz, 21-V-rms ac signals with +/- 35-V dc potentials are used as power supplies to transfer up to 6-W RF ablation signals with 120-V-pp swing while keeping the maximum dc supply voltages of the ICs less than the breakdown voltage of 70 V. The proposed RDN IC fabricated using a 0.18-mu m high-voltage bipolar, CMOS, LDMOS (HV BCDMOS) occupies an area of 2.1 mm(2).
3.125-to-28.125 Gb/s 4.72 mW/Gb/s Multi- Standard Parallel Transceiver Supporting Channel-Independent Operation in 40-nm CMOS
No full textThis paper presents a 3.125-to-28.125 Gb/s dual-lane multi-standard parallel transceiver supporting channel-independent operation. Network equipment supports multiple data rates to encompass diversified communication standards. However, network equipment supports only a fixed number of channels at each supported data rate. This lack of flexibility limits the utilization rate of the network equipment. This study proposes a clock and data recovery (CDR) IC to obtain utilization flexibility and scalability in each channel with complete channel independency. The CDR IC achieves a wide tuning capability for data rates ranging from 3.125 to 28.125 Gb/s with low clock jitter owing to the use of injection-locked oscillators in each channel. Each CDR lane generates a channel-independent injection clock signal with a fixed-frequency global clock signal using a variable clock divider and a phase rotator with the proposed harmonic distortion compensator. In addition, a frequency tracking loop is proposed using a bang-bang phase detector-based natural frequency detector to align the natural frequency of the injection-locked oscillator with the input data rate, thereby suppressing the injection spur. The test chip fabricated in a 40 nm CMOS exhibits a power efficiency of 4.72 mW/Gb/s, while generating a recovered clock jitter of 976 fs(rms) at a data rate of 25.78125 Gb/s.
A Framed-Pulsewidth Modulation Transceiver for High-Speed Broadband Communication Links
No full textA 20 Gb/s serial link transceiver employing a framed-pulsewidth modulation (FPWM) scheme that overcomes the signal-to-noise (SNR) degradation without a linearity requirement is presented. The FPWM scheme encodes data at the location and the width of the pulses in a frame spanning multiple unit intervals (UI) while maintaining a minimum pulsewidth equal to 1 UI. The test chip achieves a coding gain of 33 %, which allows a total throughput of 20 Gb/s while keeping the baud rate of 15 Gb/s. The equalization core incorporating programmable 3-tap pre-emphasis at the transmitter and a continuous-time linear equalizer (CTLE) at the receiver compensates for the channel insertion loss up to 12 dB at the baud frequency, and achieves < 10(-12) of bit error rate (BER). The transceiver IC, fabricated in 40 nm CMOS, occupies 2.2x 0.48 mm(2) and consumes 90.6 mW from a 0.9 V supply which renders the power efficiency of 4.53 mW/Gb/s.
Fast-settling Onboard Electrochemical Impedance Spectroscopy System Adopting Quasi-linear-phase Band-pass Filter
No full textElectrochemical impedance spectroscopy (EIS) is a non-invasive tool capable of characterizing batteries' states based on impedance over a specific frequency range. Considering that the use of lithium-ion batteries with large capacity in many electric vehicles imposes an extremely high impedance measurement accuracy in a range of sub-mΩ, EIS systems widely use a digital lock-in amplifier (DLIA) that allows ultra-precision impedance measurement at the cost of a long settling time. This work presents an onboard EIS system with further reduced measurement time. In the proposed EIS system, the DLIA embedding of a pair of quasi-linear-phase band-pass filters is utilized to shorten the settling time by widening the bandwidth of the noise suppression low-pass filter with minimum accuracy degradation. Compared to the EIS systems using the conventional DLIA, this work achieves a 45% and 57% reduction in the estimated settling time over the frequency range of 1-to-1000 Hz and at the lower bound (1 Hz), respectively
Liquid dielectric layer-based microfluidic capacitive sensor for wireless pressure monitoring
No full textMicrofluidic capacitive sensors with enhanced performance and wireless sensing capability present great ad-vantages for various pressure sensor applications. In this work, a liquid dielectric layer (LDL)-based wireless capacitive sensor for high sensitivity and low-pressure detection has been demonstrated. The wireless capacitive sensor was designed based on an LC resonant circuit model and integrated into a microfluidic device by intro-ducing liquid-metal Galinstan into polydimethylsiloxane (PDMS) microchannels. The effect of various dielectric mediums (air, deionized (DI) water, and saline) on the performance of the capacitive sensor was characterized to study the sensitivity and robustness of the devices. Moreover, the high permittivity of liquid dielectric mediums enhances the sensitivity of the pressure sensor. The sensitivities of 0.0043 kPa-1, 0.0111 kPa-1, and 0.0125 kPa-1 were achieved for air, DI water, and saline-based dielectric mediums, respectively, for a low-pressure region of 0-10 kPa. Furthermore, we fabricated the wireless pressure sensor in three different form factors to enhance the applicability of the flexible wireless sensor. We also demonstrated the possibility of wirelessly monitoring human motion through real-time pressure detection using capacitive sensors fabricated with a liquid dielectric medium. The proposed LDL-based capacitive sensor, with high sensitivity, could be a potential candidate for low-pressure sensor applications, especially in detecting subtle pressure from the human body.
ASIL-D and AEC-Q100 Grade 0 Compliant Automotive RC Oscillator with Farey Sequence-based Calibration
No full textIn vehicle electrification, safety remains a top priority. High safety applications must meet AEC-Q1 00 Grade 0 and ASIL-D standards, requiring circuits operating in temperatures from -40°C to 150°C, and employing two physically isolated systems for cross-validation. Battery management systems in electric vehicles consist of multiple battery monitoring ICs (BMICs) [1], each featuring dual isolated systems to validate measurements, communication, and oscillator functions (Fig. 1). Oscillator accuracy, critical for measurement and communication, must satisfy specific standards depending on the communication protocol. Low-speed automotive communication standards like CAN/LinBus accept sub-1% inaccuracy. However, to achieve sub-1% inaccuracy within a wide temperature range and dual-isolated architecture, extensive trimming incurs significant costs that scale with the number of BMICs. Therefore, there's an urgent need to develop oscillators that achieve sub-1% inaccuracy while minimizing trimming efforts. RC oscillator (RCO) is a promising option. Previous closed-loop architectures achieved high accuracy, but required costly high-bit, multi-point trimming [2]-[3]. Alternative open-loop architectures reduced manual trimming burden, but struggled to attain sub-1% inaccuracy [4]-[5]. The current-calibration method [5] can improve accuracy by increasing the current-steering DAC (IDAC) bits at the cost of doubling the area and causing mismatch issues, necessitating extra manual trimming
Measurement of Blood Pressure via a Skin-Mounted, Non-Invasive Pressure Sensor
No full textTraditional methods to measure blood pressure are intermittent and may fail to detect the critical blood pressure fluctuations. Continuous blood pressure monitoring offers important clinical value in predicting cardiovascular diseases. Invasive (i.e., artery cannulation) and noninvasive approaches (e.g., volume clamping, pressure sensor, ultrasound, and optical methods) have limitations that prevent their generalized use outside of controlled settings, and few account properly for changes in the properties of the arteries (e.g., after drug administration, aging). This article proposes a method that combines a skin-interfaced pressure sensor with a sensor of pulse wave velocity, to continuously, noninvasively, and accurately measure the blood pressure, in ways that eliminate drifts and other artifacts that can prevent accurate, longitudinal monitoring. A scaling law is established to show that, for a linearly proportional relationship between the blood pressure and sensor pressure, the coefficient of proportionality depends on the elastic moduli E-artery and E-tissue of the artery and tissue, respectively, and the artery thickness h(artery) and radius R-artery via a single, dimensionless combination, E(artery)h(artery)/(EtissueRartery), i.e., the normalized artery stiffness. This scheme determines the blood pressure in a manner that explicitly accounts for changes in the artery elastic modulus and thickness (e.g., due to the administration of drugs, aging).
Recent Advances in Bioresorbable Biomedical Applications: From Materials to Devices
No full textWearable and implantable devices provide users with continuous monitoring and treatment, and bioresorbable features can facilitate the use of temporary biomedical devicesand reduce electronic wastes (e-wastes). Bioresorbable metals and polymers offer multiple benefits, such as high conductivity and mechanical support, for skin-interfaced and implantable biomedical devices in versatile biomedical applications. These materials dissolve naturally after their targeted lifetime, avoiding complications arising from retrieval surgeries and preventing e-waste accumulation. This review summarizes recent advances in both bioresorbable materials and devices, highlighting various polymers, semiconductors, and metal options along with their dissolution processes. The following contents introduce the current developments in bioresorbable skin-interfaced and implantable systems including electrostimulation (ES), energy harvesting, sensor, and transistor systems. A concluding section discusses current challenges and future research opportunities in this field.
3D-Printed CNT-Reinforced Bioresorbable Vascular Scaffold with Enhanced Mechanical Stability and Integrated Wireless Pressure Sensor for Continuous Hemodynamic Monitoring
No full textPolymer-based bioresorbable vascular scaffolds (BVS) have garnered significant attention in biomedical applications. Among various BVS, polycaprolactone (PCL)-based scaffolds exhibit excellent biocompatibility, flexibility, chemical stability, and controlled degradation. However, their low radial strength limits practical applicability. Moreover, most reported BVS require periodic postimplantation monitoring to enable early detection of in-stent restenosis and thrombosis. To overcome these limitations, we fabricate a carbon nanotube (CNT)-reinforced PCL BVS using a 3D printing process, enabling patient-specific customization while significantly improving mechanical strength and durability. The proposed PCL/CNT-based stent not only serves as a structural scaffold but also facilitate real-time vascular pressure monitoring by integrating a wireless LC capacitive pressure sensor. The LC pressure sensor is microfabricated using microelectromechanical systems (MEMS) technology and exhibits highly stable resonance characteristics. A key innovation is the integration of a supporting micropillar within the capacitor cavity, which minimizes structural deformation and ensures a stable capacitance response. Mechanical testing demonstrates that PCL/CNT stents achieve significantly higher radial force (0.1 N/mm) compared to pristine PCL (0.013 N/mm). The wireless sensor exhibits high sensitivity (49 kHz/mmHg) with minimal capacitance variation (+/- 5%). In-vitro studies in a phantom experiment confirm stable resonance frequency fluctuations that accurately correlate with hemodynamic changes. This smart stent integrates biodegradable nanocomposites, 3D printing, and wireless sensing, providing a noninvasive platform for restenosis and thrombosis monitoring. It marks a significant advancement in cardiovascular implants, paving the way for personalized and proactive patient care.
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