In this paper, the guidelines to design a true random bit generator (TRBG) circuit with a predefined minimum entropy are discussed. The approach is proposed for a TRBG based on a one-dimensional piecewise-linear chaotic map; it does not require bit throughput reduction, and it is suitable for the development of integrated TRBG circuits. In particular, the proposed design strategy is based on a feedback control procedure that allows to dynamically change the system parameters for the correction of the circuit "nonidealities" (e.g., the circuit offsets). The correction algorithm does not require a direct measurement of the system "nonidealities" or of the effective value of the map parameters, but only a dynamic estimation of these quantities based on the observation of the TRBG output. The design approach is validated by a hardware prototype implemented on a field-programmable analog array. The results of the NIST FIPS 140-2 test suite, the DIEHARD test suite, and the Coron's Universal test, applied to the TRBG output sequences before and after a simple post processing without throughput reduction, are reported and discussed.

In this paper, a family of nonlinear congruential generators (NLCGs) based on the digitized Reacutenyi map is considered for the definition of hardware-efficient pseudorandom number generators (PRNGs), and a theoretical framework for their study is presented. The authors investigate how the nonlinear structure of these systems eliminates some of the statistical regularities spoiling the randomness of sequences generated with linear techniques. In detail, in this paper, a necessary condition that the considered NLCGs must satisfy to have maximum period length is given, and a list of such maximum period PRNGs for period lengths up to 2³¹-1 is provided. Referring to the NIST800-22 statistical test suite, two PRNG examples are presented and compared to well-known PRNGs based on linear recurrencies requiring a similar amount of resources for their implementation

In this paper, a new version of the field-mill sensor structure for atmospheric electric field measurements is presented. Both the hardware components (i.e., the mechanical structure, the electronic front end, and the acquisition and control systems) and the data processing software are designed in order to reduce power consumption and enhance the instrument metrological performance in terms of accuracy, sensitivity, and frequency band.

This paper shows the feasibility of a High Frequency RFID passive sensor tag equipped with sensors based on a thin film circuit on a Si substrate for the measurement of the soil moisture. Three tags embedding different sensing systems compliant with the energy harvesting requirements were developed. The used sensors were previously characterized with the aim of tailoring an adequate electronic front-end. All the typical solutions for soil moisture detection were implemented: a fringe capacitance sensor, a soil impedance sensor and finally a humidity sensor based on functionalization with TiO2 nano particles. The obtained results prove that the conceived solution is satisfactory and that the sensors have good sensing properties. The proposed system can be applied within the IoT framework in manifold monitoring scenarios of soil moisture sensing.

Wireless sensor networks for home automation or environment monitoring require low-cost low-power sensors. Carbon monoxide (CO) metal-oxide (MOX) sensors could be suitable in terms of device cost, but they show some severe limits, such as the need to be heated, which means large power consumption and the need for complex and frequent calibration procedures, which increases the overall cost. This paper investigates the possibility to partially overcome these limits by a low-cost detection system based on a suitable commercial sensor (TGS 2442, Figaro, Inc.) and an ad hoc measurement technique exploiting specifically tailored temperature profiles. To this aim, the authors study the dynamic behavior of low-power CO MOX sensors operated with pulsed temperature profiles by means of two approaches: 1) sensor modeling and 2) experimental evaluation. To analyze how the sensor dynamic response changes as a function of the CO concentration, the authors individuate a temperature profile, which ensures satisfactory sensitivity to the target gas and very low power consumption. Moreover, some parameters describing the sensor response shape are selected, which prove to be significant in terms of both robustness to environmental conditions and calibration simplicity.