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A Hybrid Recording System with 10kHz-BW 630mVPP84.6dB-SNDR 173.3dB-FOMSNDRand 5kHz-BW 114dB-DR for Simultaneous ExG and Biocurrent Acquisition

2024-02-20T15:00:00Z

Title: A Hybrid Recording System with 10kHz-BW 630mVPP84.6dB-SNDR 173.3dB-FOMSNDRand 5kHz-BW 114dB-DR for Simultaneous ExG and Biocurrent Acquisition Author(s): Seol, Taeryoung; Kim, Geunha; Lee, Sehwan; Kim, Samhwan; Kim, Dong Wook; Wie, Jeongyoon; Shin, Yeon Jae; Kang, Hongki; Jang, Jae Eun; George, Arup Kocheethra; Lee, Junghyup Abstract: As the precise acquisition of continuous ExG (ENG, ECG, etc.) and biocurrent (chemical, PPG, etc.) signals provides further insights into chronic health conditions [1,2], a lowpower readout system capable of simultaneously recording ExG and biocurrent signals with high precision is beneficial (Fig. 33.11.1(a)). Such a system requires BW>5kHz, noise floor ~100nV/√Hz, and FOMSNDR>170dB to cover the entire ExG spectrum. Also, an input range (IR)>100mVPP is necessary to prevent saturation. Likewise, for biocurrent acquisition, a system has to meet BW>1kHz, noise floor ~1pArms/√Hz, and DR>100dB to detect small charge perturbations without saturation from large baseline currents. Extensive effort has been conducted to design a simultaneous V & I monitoring system (Fig. 33.11.1(b)). For instance, [1] allows the design of a simultaneous V & I monitoring system based on simple integration of individual readout schemes. However, this system consumes power >100μW and is unsuitable for simultaneous ExG and biocurrent signals due to the limited BW. Although [2] achieves wide BW for both signals, it cannot record V & I simultaneously due to the time-division manner and also has narrow IRs. On the other hand, [3] employing frequency division, achieves simultaneous readout while consuming low power. However, it is vulnerable to artifacts, while the BW of each V & I readout limits the other. This paper presents a simultaneous V & I recording system using a single 2nd-order continuous-time ΔΣ modulator (CT-DSM). Such simultaneous recording is achieved by using a highly linear hybrid GmC integrator with a triplet VCObased quantizer, where the differential voltage and single-ended current are combined into differential and common mode signals (Fig. 33.11.1 (c)). © 2024 IEEE.

Optimization of Inkjet-Printed Seed Layer Based Flexible, Transparent Metal Electrode for Bio-Signal Sensing

2023-07-09T15:00:00Z

Title: Optimization of Inkjet-Printed Seed Layer Based Flexible, Transparent Metal Electrode for Bio-Signal Sensing Author(s): Kim, Duhee; Kim, Boil; Hong, Nari; Choe, Han Kyoung; Kang, Hongki Abstract: A micro-electrode array (MEA) is essential in the bio-medical field to measure various bio-signals in vitro and in vivo environments. The transparent MEA allows imaging of cell surfaces and organs inside the body. Also, when we perform light-based modulation, such as optogenetics, higher efficiency in response to light can be obtained with a transparent MEA. Here, instead of well-known direct electrode material printing, we print a polymer seed layer that can induce the formation of transparent ultrathin (< 10 nm) metal electrodes with the merits of fabrication simplicity, low processing temperature, and design customizability. We optimized Au deposition thickness and metal film morphology to form conductive and transparent electrodes on selectively printed polymer seed layer regions. These electrodes show improved impedance at low frequencies compared to well-known thick Au-based electrodes. Finally, we successfully recorded brain signals in vivo by placing the flexible electrode array on the surface of the mouse brain. © 2023 IEEE.

Massive Fabrication of Carbon Nanotube Transistors by Surface Tension-Driven Inkjet-Printing Method

2023-07-09T15:00:00Z

Title: Massive Fabrication of Carbon Nanotube Transistors by Surface Tension-Driven Inkjet-Printing Method Author(s): Park, Soohyun; Shin, Minhye; Kang, Hongki; Lee, Yoonhee Abstract: Carbon nanotube field-effect transistors (CNTFETs) have been ideal nanoelectronics in semiconductor technologies with exceptional electrical properties. Scaling the CNT -FET fabrication enables the expansion of the application fields. However, placing nanotubes with uniform alignment and controlled density to the electrode contacts has been the maj or challenge in massive manufacturing. Here, we introduce the in-place inkjet-printing method for fabricating CNTFETs with controlled numbers of connected CNTs at a single CNT level. A picoliter (pL) drop of CNT ink is printed to the pre-patterned electrode arrays in parallel over a four-inch silicon wafer, allowing adaptive manufacturing without additional lithographic processes. Drops form thin films on the metal electrode patterns driven by the surface tension flow, diluting the surface density of CNT on the one-micrometer channel gap and avoiding bundled coffee ring edges. Finally, single CNTs are correctly bridged to the electrodes with high statistical yield. This process enables reproducible and high-throughput single CNT deposition, integrating into the FET manufacturing process, and can be used for versatile nanoelectronics applications, such as biosensors. © 2023 IEEE.