RF Wireless Power Transfer for EIT Neonate Lung Function Monitoring

This paper presents an antenna-based RF wireless power and data transfer system for wireless neonate lung function monitoring in an intensive care unit using electrical impedance tomography (EIT). The proposed dual-band system comprises a directional slotted patch transmit antenna and a slotted flexible omnidirectional monopole antenna operating at 2.51 GHz and 5.1 GHz. A slotting technique unique to each antenna is proposed to achieve dual-band operation and size miniaturization for each antenna. Also, the arraying technique combined with parasitic elements is employed to increase the receive antenna gain and in turn the received power level. Both transmit and receive antennas were simulated and fabricated. Following FCC safety regulations, measurements show 20 mW received power when the receiver and the transmitter are spaced 19 cm apart

Electrical Impedance Tomography for Biomedical Applications: Circuits and Systems Review

There has been considerable interest in electrical impedance tomography (EIT) to provide low-cost, radiation-free, real-time and wearable means for physiological status monitoring. To be competitive with other well-established imaging modalities, it is important to understand the requirements of the specific application and determine a suitable system design. This paper presents an overview of EIT circuits and systems including architectures, current drivers, analog front-end and demodulation circuits, with emphasis on integrated circuit implementations. Commonly used circuit topologies are detailed, and tradeoffs are discussed to aid in choosing an appropriate design based on the application and system priorities. The paper also describes a number of integrated EIT systems for biomedical applications, as well as discussing current challenges and possible future directions

Live Demonstration: Performance Evaluation of Electrical Impedance Tomography Systems using a Color-Coded Full Reference SNR Method

A color-coded full reference signal-to-noise (FR-SNR) method is proposed as a simple and reproducible performance evaluation method for EIT systems. It will be demonstrated with a 16-electrode high-speed EIT system and a resistive phantom. The performance of the EIT system can be altered by artificially introducing non-ideal operating conditions such as low drive current, low ADC resolution, dc offset in the readout front-end and large electrode impedance. The performance under these conditions will be measured and displayed using the FR-SNR method

An active microchannel neural interface with artifact reduction

High-density neural electrodes in microchannel interfaces require in-situ amplification of the neural signals and rejection of high-voltage stimulus pulses leaking to the channel in order to adequately detect neural signals in the presence of concurrent stimulation. This paper presents the design of an active microchannel neural interface in 0.18 μm CMOS employing neural recording and stimulation. To reduce stimulus artifacts, a novel method is proposed that disconnects the recording module during concurrent channel stimulation and automatically applies detection and reduction of stimulus artifacts from adjacent channels using a tunable filter. Simulations show that the method provides at least 54 dB artifact attenuation

Towards a Universal Methodology for Performance Evaluation of Electrical Impedance Tomography Systems using Full Reference SNR

This paper describes a simple and reproducible methodology towards a universal figure-of-merit (FoM) for evaluating the performance of electrical impedance tomography (EIT) systems using reconstructed images. Based on objective full-referencing and signal-to-noise ratio, the method provides a visually distinguishable hot-map and two new FoM factors, to address the issues where common electrical parameters are not directly related to the quality of EIT images. The paper describes the method with simulation results and develops a 16 electrode EIT system using an ASIC front-end for evaluation using the proposed method. The measured results show both visually and in terms of the proposed FoM factors, the impact on recorded EIT images with different current injection amplitudes

A DC Model for Organic Electrochemical Transistors and Analysis of Their Performance as Voltage Amplifiers

Organic electrochemical transistors (OECTs) have received significant attention especially in biomedical applications. Despite many efforts on modeling these transistors, simulating OECT-based circuits is still a challenge due to the absence of accurate mathematical models. In this paper a DC model for p-type depletion-mode OECTs is proposed that more closely mimics their characteristics compared to the Bernards-Malliaras (B-M) model. Although OECTs are mostly used as transconductance amplifiers, their use as voltage amplifiers is investigated here with measurements at various drain-source voltages. Compared to the B-M model, the proposed model has better matching up to 3.6% between simulations and measurements of the analyzed transistors