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A Duty-Cycled CTDSM with Scalable Bandwidth and Power for ExG Biopotential Acquisition
No full textADC, DSM, Bio-Sensor, Analog Front Ends, ExG Biopotential, Bandwidth Power Scalable, Duty CyclingThis paper introduces a continuous-time (CT) delta-sigma analog-to-digital converter (ADC) integrated with a capacitively-coupled chopper instrumentation amplifier (CCIA) for ExG biopotential recording system, offering duty-cycled operation with scalable bandwidth and power consumption. The system achieves scalable bandwidth by adjusting the integrator's load capacitance and the center frequency of the body-driven voltage- controlled oscillator (VCO). By making the bandwidth scalable, power consumption in the analog part can be reduced through the gain-bandwidth product and power trade-off, while in the digital part, dynamic power consumption can be minimized by changing the sampling frequency. Moreover, power efficiency is enhanced through duty-cycled operation, which minimizes unnecessary power dissipation during low-frequency signal recording in conventional systems. The proposed design satisfies the critical requirements for noise performance, power consumption, input range, and input impedance to support diverse bio-signal recordings. The proposed system, fabricated in the 0.18 μm standard CMOS process, achieves FoMSNDR,1 kHz = 170.3 dB for a 1 kHz bandwidth and FoMSNDR,10 kHz = 170.1 dB for a 10 kHz bandwidth. It consumes 2.8 μW of power for the 1 kHz bandwidth and 4.5 μW for the 10 kHz bandwidth, operating at a supply voltage of 0.6 V. The design occupies an active area of 0.138 mm².
Keywords : Continuous time delta sigma modulator, neural recording analog front ends, bandwidth and power scalable, duty-cycled operation|본 논문에서는 ExG 생체신호 기록 시스템을 위한 듀티 사이클링을 적용하고 대역폭 및 전력 소비가 조절 가능한 연속 시간 델타-시그마(CTΔΣ) 아날로그-
디지털 변환기(ADC)를 제안한다.
제안된 시스템은 Gm-C 적분기의 부하 커패시터 용량과 바디-드리븐 전압 제어 발진기(VCO)의 중심 주파수를 조절함으로써 대역폭을 10배 조절할 수 있으며, 듀티 사이클 운영 방식을 통해 기존 시스템에서 신호 기록 시 불필요한 전력 소모를 최소화한다. 또한, 저잡음 전류 재사용 증폭기 단계, 바디-드리븐 VCO 기반 양자화, 그리고 PIIB를 결합하여 높은 입력 임피던스, 넓은 입력 범위, 탁월한 잡음 성능을 달성하였다.
본 설계는 0.18 μm 표준 CMOS 공정을 사용하여 구현되었으며, 활성 면적은 0.138 mm²이다. 구체적으로, 시스템은 0.6 V 전원에서 동작하며, 1 kHz 대역폭에서는 2.8 μW, 10 kHz 대역폭에서는 4.5 μW의 전력을 소비하고, 각각 FoMSNDR은 170.3 dB 및 170.1 dB를 달성하였다. 이러한 결과는 제안된 시스템이 대역폭 및 전력 조절, 듀티 사이클 방식의 전력 소모의 최소화와 함께 ExG 기록 시스템의 엄격한 요구사항을 효과적으로 충족함을 입증하며, 다양한 생체신호 모니터링 응용에 실용적이고 효율적인 해결책을 제공함을 보여준다.
핵심어 : ADC 기반의 생체신호 기록 시스템, 대역폭/전력 가변 가능성Ⅰ. Introduction 1
1.1 Motivation 1
1.2 Design Considerations 3
1.3 Background 5
Ⅱ. Proposed ExG Biopotential Recording System 10
2.1 Proposed System 10
2.1.1 Overall Architecture 10
2.1.2 Bandwidth and Power Scalability 15
2.1.3 Design of an Integrator 17
2.1.4 Duty-cycled operation 21
2.1.5 Design of a VCO Quantizer· 24
2.2 Proposed Chip Micrograph 27
III. Measurement Results 29
IV. Conclusion 36
V. Reference 37MasterdCollectio
Advances in gas sensors using screen printing
No full textGas sensing is crucial for detecting and monitoring hazardous, gases in various environments to ensure safety and prevent potential health risks. It helps in the early identification of gas leaks, air quality monitoring, and environmental protection, contributing to public health and industrial safety. Screen-printed gas sensors are trending nowadays due to their ability to fabricate electrodes or deposit functional components onto substrates and their cost-effective and scalable manufacturing process, making them suitable for mass production. This review provides an overview of screen printing and hybrid screen printing techniques utilizing different methods, such as spin coating, drop casting, spray coating, and inkjet printing (IJP), with screen printing for various gas sensing applications. The mechanism of each hazardous gas detection technique, their precision in the identification of hazardous gases, and their impact on sensor enhancement were thoroughly analyzed. Furthermore, the vital integration of screen-printed gas sensors with various futuristic technologies, such as artificial intelligence (AI), machine learning (ML), and Internet of Things (IoT) devices, supercapacitors (SCs), triboelectric nanogenerators (TENGs), and microheaters, was demonstrated to enhance sensor performance and broaden the application area. Moreover, this review highlighted the importance of sensors' sensitivity, selectivity, and environmental stability, which offer plenty of room for innovation. For future improvements, the integration of microfluidic, multi-sensor arrays, functional coatings, and nanomaterials into screen-printed gas sensor devices was proposed. In this context, gas sensing platforms can be refined by operating them using energy harvesting principles, improving their environmental stability, and making them wearable and flexible. This review paper would benefit many researchers and readers working in this field to familiarize themselves with the recent breakthroughs in the rapidly emerging field of screen-printed gas sensing. © 2025 The Royal Society of Chemistry.FALSEsciescopu
Advances of triboelectric and piezoelectric nanogenerators toward continuous monitoring and multimodal applications in the new era
Get PDFBenefiting from the widespread potential applications in the era of the Internet of Thing and metaverse, triboelectric and piezoelectric nanogenerators (TENG & PENG) have attracted considerably increasing attention. Their outstanding characteristics, such as self-powered ability, high output performance, integration compatibility, cost-effectiveness, simple configurations, and versatile operation modes, could effectively expand the lifetime of vastly distributed wearable, implantable, and environmental devices, eventually achieving self-sustainable, maintenance-free, and reliable systems. However, current triboelectric/piezoelectric based active (i.e. self-powered) sensors still encounter serious bottlenecks in continuous monitoring and multimodal applications due to their intrinsic limitations of monomodal kinetic response and discontinuous transient output. This work systematically summarizes and evaluates the recent research endeavors to address the above challenges, with detailed discussions on the challenge origins, designing strategies, device performance, and corresponding diverse applications. Finally, conclusions and outlook regarding the research gap in self-powered continuous multimodal monitoring systems are provided, proposing the necessity of future research development in this field.TRUEsci
Stability and photophysical study of bright day light fluorescent material and its fabrication in laser patterning and LED application
No full textDeveloping aggregation-induced emission (AIE) active highly visible fluorescent dyes is of great importance because of its numerous applications. We have successfully developed and synthesized two novel napthalimide based molecules PU1 and PU2, that exhibit bright greenish yellow in day light and vivid green emission when exposed to UV light. Compounds PU1 and PU2 exhibit variable emission behavior at different solvent polarities. Upon raising the solvent polarity from ether to DMF, emission maxima of PU1 and PU2 underwent a bathochromic shift. Additionally, compounds PU1 and PU2 show signs of AIE, which cause a restriction in intramolecular mobility. A distinct self-assembled structure was generated at 30 % aqueous DMF solution following aggregation, as demonstrated by experiments using dynamic light scattering and field emission scanning electron microscopy. Compounds PU1 and PU2 have been blended with poly(urethane) to develop a polymeric film. Tensile strain studies, and TGA, DSC analyses were used to examine the thermal/mechanical stability of PU films. The photostability of PU1 and PU2 in both solution and polymeric film was examined using a 5-h UV-beam irradiation. Furthermore, in the presence of trifluoroacetic acid, the blended polymeric film and 365 nm LED light coated material exhibits distinct colorimetric and fluorimetric transformations. Finally, laser-induced periodic surface structure (LIPSS) pattern processing on PU1 coated substrates can be extended for optical applications. © 2024FALSEsciescopu
AdaLo: Adaptive learning rate optimizer with loss for classification
No full textGradient-based algorithms are frequently used to optimize neural networks, with various methods developed to enhance their performance. Among them, the adaptive moment estimation (Adam) optimizer is well-known for its effectiveness and ease of implementation. However, it suffers from poor generalization without a learning rate scheduler. Additionally, it has the disadvantage of a large computational burden because of individual learning rate term, as known as second-order moments of gradients. In this study, we propose a novel gradient descent algorithm called AdaLo, which stands for Adaptive Learning Rate Optimizer with Loss. AdaLo addresses two problems using its adaptive learning rate (ALR). Firstly, the proposed ALR adjusts the learning rate, based on the model's training progress, specifically the loss value. Therefore AdaLo's ALR effectively replaces traditional learning rate schedulers. Secondly, the ALR is a scalar global learning rate, reducing the computational burden. In addition, the stability of the proposed method is analyzed from the perspective of the learning rate. The superiority of AdaLo was proven by non-convex functions. Simulation results indicated that the proposed optimizer outperformed the Adam, AdaBelief, and diffGrad with regard to the training error and test accuracy. © 2024 Elsevier Inc.FALSEsciescopu
Temperature dependent thermoelectric transport in PEDOT-PSS conducting polymer: The effect of additives
Get PDFWe report on both the electrical and thermoelectric transport properties as a function of temperature in poly(3,4-ethylene dioxythiophene) (PEDOT)-poly(styrene sulfonate) conducting polymers for a wide range of dimethyl sulfoxide (DMSO) additives. Whereas an insulating-like electrical behavior is found over the whole temperature range, a metallic-like thermopower is mainly observed. We show that the resistivity appears to be governed by a three-dimensional variable range hopping mechanism due to disordered regions with a decreasing localization temperature T 0 and an increasing scaling factor ρ 0 as a function of the DMSO ratio. The correlation between T 0 and ρ 0 demonstrates that they are both controlled by the localization length ξ 0 , which is strongly enhanced by the DMSO in agreement with the morphological evolution of the PEDOT chains with the additive. On the other hand, the high-T positive metallic-like thermopower seems rather unaffected by the additive in contrast to its low-T counterpart, which appears negative below a characteristic temperature T s w i t c h . By showing that the latter is closely related to the localization temperature, we propose to ascribe this sign switch to the thermoelectric contribution originating from disordered regions, which competes with the metallic ones due to ordered domains. While still controlled by the localization temperature, this negative contribution appears to be consistent with a phonon-drag component with a scaling behavior as T 0 T − 3 . These analyses allow us to discuss the overall temperature dependent thermoelectric properties in a consistent way by considering a heterogeneous structure with both ordered and disordered domains. By relating explicitly the electrical resistivity to the thermopower, our results do not only reconcile these transport coefficients, but they also provide a unified picture of the properties of the conducting polymers. © 2025 Author(s).TRUEsci
Wireless and Suture-Type Strain Sensing System for Monitoring Reconstructed Soft Tissue
No full textImplantable sensor, Biocompatible fiber electrode, Wireless strain sensing, Soft tissues웨어러블 센서 및 체내삽입형 소자는 최근 고령 인구의 증가와 정확한 건강관리에 대한 수요의 증가와 맞물려 각광받고 있습니다. 이러한 많은 웨어러블 센서 및 체내삽입형 소자는 대부분 MEMS 및 반도체 공정을 기반으로 연구되고 있습니다. 그러나 이러한 소자들은 MEMS와 반도체 공정 기술을 기반으로 제작하여 대부분 이차원의 필름 형태를 가지며 이는 여러 한계점들을 가지고 있습니다. 대표적으로 표적 부위/조직과의 구조적 불일치가 발생하며 이를 해결하기 위해 추가적인 고정 방법들이 필요합니다. 그리고 대부분의 소자는 무선으로 신호 전송을 위해 PCB 회로와 추가적으로 연결하고 이는 전체 소자의 생체적합성을 떨어뜨리며 전체적인 시스템을 커지게 합니다.
본 논문은 무선 측정이 가능하면서 봉합사형의 스트레인 측정 시스템을 소개합니다. 전체 시스템은 생체적합 금 나노입자 기반 전도성 섬유로 구성되어 전체 시스템의 생체적합성을 확보하였습니다. 금 나노입자 기반 전도성 섬유는 화학적 기법을 통해 균일하게 금 나노입자들이 분포하여 낮은 수준의 저항도를 유지하고 안정적인 전기적 성능을 보여줍니다. 전도성 섬유를 중공을 가진 이중나선 구조로 고정하여 정전용량식 센서를 구성합니다. 중공을 가진 이중나선 구조 덕분에 높은 수준의 민감도를 보여줍니다. 이러한 센서를 코일과 연결하여 납땜이 없는 RLC 회로 구조의 스트레인 측정 봉합사형 시스템을 구성하였고, 센서의 정전용량 변화에 따라 시스템의 공진주파수가 변화합니다. 전체 시스템은 돼지의 아킬레스건에 삽입되어 파열 후 수술이 진행된 아킬레스건의 10주간의 회복을 관찰하였습니다. 아킬레스건의 물리적 특성을 수학적으로 분석하여 회복 기간 동안의 치유 정도를 정량화 하였습니다.|Wearable and implantable healthcare sensors are an emerging field driven by the rapid growth of the aging population and the increasing demand for precise healthcare monitoring. Recently, many wearable and implantable sensors have been developed based on MEMS and semiconductor technologies. However, these sensors face inherent limitations for clinical use due to the reliance on MEMS and semiconductor technologies, which are optimized for two-dimensional film structures. This two-dimensional structure causes a structural mismatch between film-based sensors and target organs or tissues, necessitating additional fixation methods. Furthermore, many developed sensors use PCB circuits for wireless signal transmission, which reduces the overall biocompatibility and increases the size of the system
This paper introduces a wireless strain-sensing suture system, designed to be biocompatible with conductive fibers based on gold nanoparticles. The nanoparticles are uniformly distributed through chemical methods, ensuring low resistance and stable electrical performance. These conductive fibers are arranged in a double-helix structure with a hollow core, forming a capacitive sensor with high sensitivity due to its unique design. The sensor is connected to a coil, creating a strain-sensing suture system with a solderless RLC circuit, where the system's resonant frequency varies with changes in the sensor's capacitance. This entire system was implanted in the Achilles tendon of a porcine model, enabling monitoring of recovery over a 10-week period following surgery for a ruptured tendon. The physical properties of the Achilles tendon were quantitatively analyzed to assess healing progress throughout the recovery period.List of Contents
Abstract i
List of contents ii
List of figures iii
Ⅰ. Introduction 1
Ⅱ. Research Background 4
2.1 Wearable and implantable devices 4
2.2 Soft electronics 7
2.3 Suture-type electronic system 10
2.4 This research 12
Ⅲ. Experimental Methods and Materials 14
3.1 Fabrication of AuNPs-based biocompatible fiber electrode 14
3.2 Fabrication of capacitive fiber strain sensor 15
3.3 Fabrication of wireless strain-sensing suture system 16
3.4 Characterization of fiber electrode and suture system 17
3.5 in-vivo demonstration 18
Ⅳ. Results and Discussion 19
4.1 Fabrication of biocompatible fiber electrode 19
4.2 Capacitive fiber strain sensor 22
4.3 Wireless strain-sensing suture system 25
4.4 in-vivo demonstration 29
4.5 Achilles tendon healing model 34
4.6 Long-term postoperative stiffness monitoring 37
Ⅴ. Conclusion and Future work 38
References 39
요 약 문 46MasterdCollectio
Flow4D: Leveraging 4D Voxel Network for LiDAR Scene Flow Estimation
No full textUnderstanding the motion states of the surrounding environment is critical for safe autonomous driving. These motion states can be accurately derived from scene flow, which captures the three-dimensional motion field of points. Existing LiDAR scene flow methods extract spatial features from each point cloud and then fuse them channel-wise, resulting in the implicit extraction of spatio-temporal features. Furthermore, they utilize 2D Bird's Eye View and process only two frames, missing crucial spatial information along the Z-axis and the broader temporal context, leading to suboptimal performance. To address these limitations, we propose Flow4D, which temporally fuses multiple point clouds after the 3D intra-voxel feature encoder, enabling more explicit extraction of spatio-temporal features through a 4D voxel network. However, while using 4D convolution improves performance, it significantly increases the computational load. For further efficiency, we introduce the Spatio-Temporal Decomposition Block (STDB), which combines 3D and 1D convolutions instead of using heavy 4D convolution. In addition, Flow4D further improves performance by using five frames to take advantage of richer temporal information. As a result, the proposed method achieves a 45.9% higher performance compared to the state-of-the-art while running in real-time, and won 1st place in the 2024 Argoverse 2 Scene Flow Challenge(Figure presented.). © IEEE.FALSEsciescopu