Here, we report advanced materials and devices that enable high-efficiency mechanical-to-electrical energy conversion from the natural contractile and relaxation motions of the heart, lung, and diaphragm, demonstrated in several different animal models, each of which has organs with sizes that approach human scales. A cointegrated collection of such energy-harvesting elements with rectifiers and microbatteries provides an entire flexible system, capable of viable integration with the beating heart via medical sutures and operation with efficiencies of ∼2%. Additional experiments, computational models, and results in multilayer configurations capture the key behaviors, illuminate essential design aspects, and offer sufficient power outputs for operation of pacemakers, with or without battery assist.

https://www.pnas.org/content/pnas/111/5/1927.full.pdf

Conformal piezoelectric energy harvesting and storage from motions of the heart, lung, and diaphragm

This paper presents a low power boost converter for thermoelectric energy harvesting that demonstrates an efficiency that is 15% higher than the state-of-the-art for voltage conversion ratios above 20. This is achieved by utilizing a technique allowing synchronous rectification in the discontinuous conduction mode. A low-power method for input voltage monitoring is presented. The low input voltage requirements allow operation from a thermoelectric generator powered by body heat. The converter, fabricated in a 0.13 μm CMOS process, operates from input voltages ranging from 20 mV to 250 mV while supplying a regulated 1 V output. The converter consumes 1.6 (1.1) μW of quiescent power, delivers up to 25 (175) μW of output power, and is 46 (75)% efficient for a 20 mV and 100 mV input, respectively.

A 20 mV Input Boost Converter With Efficient Digital Control for Thermoelectric Energy Harvesting

This paper presents a physically based model for the metal-oxide-semiconductor (MOS) transistor suitable for analysis and design of analog integrated circuits. Static and dynamic characteristics of the MOS field-effect transistor are accurately described by single-piece functions of two saturation currents in all regions of operation. Simple expressions for the transconductance-to-current ratio, the drain-to-source saturation voltage, and the cutoff frequency in terms of the inversion level are given. The design of a common-source amplifier illustrates the application of the proposed model.

An MOS transistor model for analog circuit design

The selection of drain current, inversion coefficient, and channel length for each MOS device in an analog circuit results in significant tradeoffs in performance. The selection of inversion coefficient, which is a numerical measure of MOS inversion, enables design freely in weak, moderate, and strong inversion and facilitates optimum design. Here, channel width required for layout is easily found and implicitly considered in performance expressions. This paper gives hand expressions motivated by the EKV MOS model and measured data for MOS device performance, inclusive of velocity saturation and other small-geometry effects. A simple spreadsheet tool is then used to predict MOS device performance and map this into complete circuit performance. Tradeoffs and optimization of performance are illustrated by the design of three, 0.18-mum CMOS operational transconductance amplifiers optimized for DC, balanced, and AC performance. Measured performance shows significant tradeoffs in voltage gain, output resistance, transconductance bandwidth, input-referred flicker noise and offset voltage, and layout area.

/pdf/tradeoffs-and-optimization-in-analog-cmos-design-2vmcctfb10.pdf

Tradeoffs and Optimization in Analog CMOS Design

Pythium insidiosum: an overview.

Quillaja saponins have an intrinsic capacity to interact with membrane lipids that self-assembles in nanoparticles (immunostimulating complexes or ISCOM-matrices) with outstanding immunoadjuvant activity and low toxicity profile. However, the expensive and laborious purification processes applied to purify Quillaja saponins used to assemble ISCOM-matrices show an important drawback in the large-scale use of this vaccine adjuvant. Thus, in this study, we describe a protocol to appropriately formulate ISCOM-matrices using the raw aqueous extract (AE) of Quillaja lancifolia leaves. In the presence of lipids, AE was able to self-assemble in nanostructures that resembles immunostimulating complexes (ISCOM). These negatively charged nanoparticles of approximately 40 nm were characterized by transmission electron microscopy and dynamic light scattering. In addition, well-known saponins with remarkable immunoadjuvant activity, as QS-21, were detected into nanoparticles. Thus, the easier, robust, cheaper, and environmentally friendly method developed here may be an alternative to the classical methods for ISCOM-matrices production that use high-purified saponins. 

/pdf/iscom-matrices-nanoformulation-using-the-raw-aqueous-extract-1ffy9ug2.pdf

ISCOM-Matrices Nanoformulation Using the Raw Aqueous Extract of Quillaja lancifolia (Q. brasiliensis)

We are very pleased to present to the readers of the Springer Journal on Analog Integrated Circuits and Signal Processing a selection of extended papers from the 5th edition of the IEEE Latin America Symposium on Circuits and Systems LASCAS 2014, held in Santiago de Chile, Chile, from Feb. 26th to 28th, 2014. 155 papers coming from authors from 32 countries, 22 of them from outside Latin American, were submitted to the conference. After a thorough review process 83 papers were accepted for presentation at the conference and publication in the IEEE LASCAS Proceedings. Based on the evaluations of the Program Committee members and the corresponding session chairs, a total of 22 of these works were invited to submit a substantially extended and revised manuscript to this Special Issue of LASCAS 2014. These papers went through a second-round of peer-review process and 14 papers were finally selected for this Special Issue. These contributions cover a wide range of topics within the scope of the journal, from analog circuit design to image and analog signal processing techniques and up to digital techniques and biomedical system design. In the analog circuit design domain, the papers deal with analog to digital conversion: A 2GS/s 6-bit CMOS TimeInterleaved ADC for Analysis of Mixed-Signal Calibration Techniques by Benjamı́n T. Reyes et al., voltage references: Sub-1 V Supply 5 nW 11 ppm/C Resistorless SubBandgap Voltage Reference by Oscar E. Mattia et al. and ultra low-voltage oscillators: Analysis and Design of a Fully-Integrated Colpitts Oscillator Operating at UltraLow-Voltages by Marcio Bender Machado et al. Two papers address topics on analog circuits for power management: A Series-Parallel Switched Capacitor Step-Up DC-DC Converter and its Gate-Control Circuits for Over the Supply Rail Switches by Pablo Pérez-Nicoli et al and A Power Management System Architecture for LF Passive RFID tags by Fernando Paixão Cortes et al. One paper analyzes techniques for energy harvesting: Electrostatic energy harvesting using capacitive generators without control circuits by Antonio Carlos M. de Queiroz. Device modeling with analog application is considered in A fully symbolic homotopy-based memristor model for applications to circuit simulation by Arturo Sarmiento et al. Analog signal processing is dealt with in Two-Dimensional Analog Signal Processing and Its Implications on Circuit Theory by Shervin Erfani et al., and image and video processing in CMOS Imager with Current-Mode Sub-Band Image Coding at the Focal Plane by Bruno Bastos Cardoso et al and Towards Optimal Use of Pel Decimation to Trade off Quality for Energy by Ismael Seidel et al. Two works are related to digital techniques: High-Performance Elliptic Curve Cryptoprocessors over GF(2m) on Koblitz Curves by Paulo C. Realpe-Muñoz et al and Automatic Complex Instruction Identification for Efficient Application Mapping onto Application-Specific Instruction Set Processors by Alexandre S. Nery et al. Two papers are related to biomedical system design: A Novel 915 MHz, RFID-based & Fernando Silveira silveira@fing.edu.uy

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Special issue: highlights from the IEEE Latin American Symposium on Circuits and Systems (LASCAS) 2014

Video search has become a very important tool, with the ever-growing size of multimedia collections. This work introduces our Video Semantic Indexing system. Our experiments show that Residual Vectors provide an efficient way of aggregating local descriptors, with complementary gain with respect to BoVW. Also, we show that systems using a limited number of descriptors and machine learning techniques can still be quite effective. Our first participation at the TRECVID evaluation has been very fruitful: our team was ranked 6 in the light version of the Semantic Indexing task.

/pdf/the-stanford-technicolor-fraunhofer-hhi-video-semantic-4zzriqwzjc.pdf

The Stanford/Technicolor/Fraunhofer HHI Video Semantic Indexing System.

All inversion region CMOS design and the gm/ID method have been previously applied to achieve optimized RF CMOS designs for circuits, such as an LNA, with performance determined by the linearized, small signal, parameters of the transistor. In this work we show that this approach is very useful also in the case of an envelope detector, whose operation is based on the second order non-linear behavior of the transistor (determined by the second derivative of the current vs. voltage characteristic). A semi-empirical, look-up table based, model of the MOS transistor is applied. Through it, it is determined the inversion level (directly related to the gms/ID ratio) where the conversion gain is maximized. A novel figure of merit that only depends on the inversion level is proposed to aid the design. The predictions are verified against measurements results, both at the transistor and circuit level. The considered circuit is a MOS Envelope Detector with on-chip matching network for 2.4GHz in 0.13 m CMOS technology.

Fernando Silveira

Papers

ISCOM-Matrices Nanoformulation Using the Raw Aqueous Extract of Quillaja lancifolia (Q. brasiliensis)

Special issue: highlights from the IEEE Latin American Symposium on Circuits and Systems (LASCAS) 2014

The Stanford/Technicolor/Fraunhofer HHI Video Semantic Indexing System.

RF CMOS all inversion region design based on gm/ID: the non-linear case of an envelope detector

Conception optimale et réutilisable d'OTAs pour dispositifs médicaux implantables