A Supply-voltage driving scheme for grounded capacitive sensor front-ends

n this article, a novel supply-voltage driving1 (SVDR) scheme for capacitive sensor front-ends is proposed to2 eliminate the parasitic capacitance effects. The suggested circuit3 is intended for remote sensors (and, hence, connected to the4 circuit through a shielded cable) with one electrode grounded5 and of low capacitance (in the 0–10-pF range). The effects of6 the parasitic capacitance of the cable are avoided using the7 active-shielding technique, whereas those of the amplifier input8 through a smart driving of the reference node of the amplifier9 supply voltage. Thanks to these techniques, the input–output10 characteristic shows, without applying any adjustment and/or11 calibration, an offset error lower than 3 fF. The nonlinearity12 error (NLE) is in the order of 0.01% of the full-scale span (FSS),13 which corresponds to 1 fF. Different operational amplifiers (OAs)14 and different lengths (up to 15 m) of the interconnecting cable15 are experimentally tested to demonstrate the feasibility of the16 circuit. In comparison with similar circuits recently suggested in17 the literature, the proposed circuit does not require any bulky18 component, such as a transformer, and consequently, it is a19 lower-cost solution and suitable to be integrated.Peer ReviewedPostprint (published version

A wearable low-power and low-cost electromyographic sensor for arm prosthesis

Abstract— This work presents the design considerations for an electromyographic (EMG) sensor destined to be integrated in a low-cost robotic arm prosthetic for below-elbow amputation, which is being developed in Paraguay by a multidisciplinary teamwork. The design exposed on this paper is addressed to optimize the embedded 14 bits ADC of the MSP432P401R microcontroller. It achieves the amplification and filtering of EMG signals with an input-referred noise of 1.35 μVRMS, and a CMRR greater than 95 dB, with a very low quiescent current consumption of 40 μA. The sensor also includes a common-mode feedback circuit that drives a reference electrode.Este trabajo presenta las consideraciones de diseño para un sensor de señales de electromíograma (EMG), diseñado para ser integrado en una prótesis robótica de bajo costo, para amputaciones bajo codo, que está siendo desarrollada en Paraguay por un equipo de trabajo multidisciplinario. El diseño presentado está dirigido a optimizar el rango dinámico del ADC embebido en el microcontrolador MSP432P401R de Texas Instruments. El sensor efectúa la amplificación y el filtrado de las señales de EMG con un ruido referido a la entrada de 1.35 μVRMS, un CMRR mayor a 95 dB y un muy bajo consumo de corriente, menor a 40 μA. Este también incluye un circuito de realimentación de modo común.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

A Fully-Differential Biopotential Amplifier With a Reduced Number of Parts

Objective: Fully differential topologies are well-suited for biopotential amplifiers, mainly for single-supply battery-powered circuits such as portable wearable devices where a reduced number of parts is desired. A novel fully differential biopotential amplifier is proposed with the goal of providing electrode offset rejection, bandwidth limitation, and a temporal response compliant with biomedical standards with only a single commercial quad operational amplifier (OA) integrated circuit. Methods: A novel compensation strategy was used to provide a transfer function with only one zero at the origin, which makes it easy to comply with the transient response imposed by biomedical standards. A topology with no grounded components was leveraged to obtain a common-mode rejection ratio (CMRR) ideally infinite and independent of components mismatches. Results: Design equations are presented and, as an example, an electrocardiogram (ECG) amplifier was built and tested. It features a CMRR of 102 dB at 50 Hz, 53 dB gain that supports dc input voltages up to ±300 mV when powered from a 0 to 5-V single-supply voltage, and a cutoff frequency of less than 0.05 Hz with a first order response. Conclusion: A fully differential biopotential front-end was designed and validated through experimental tests, demonstrating proper operation with only 4 OAs. Significance: The amplifier is intended for board-level design solutions, it can be built with off-the-shelf components that can be selected according to specific needs, such as reduced power consumption, low noise, or proper operation from a low-voltage power source.Fil: Spinelli, Enrique Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; ArgentinaFil: Guerrero, Federico Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; ArgentinaFil: Garcia, Pablo A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; ArgentinaFil: Catacora, Valentin Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; ArgentinaFil: Haberman, Marcelo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; Argentin

Citrus flush shoot ontogeny modulates biotic potential of <i>Diaphorina citri</i>

<div><p>The biology and behaviour of the psyllid <i>Diaphorina citri</i> Kuwayama (Hemiptera: Sternorrhyncha: Liviidae), the major insect vector of bacteria associated with huanglongbing, have been extensively studied with respect to host preferences, thermal requirements, and responses to visual and chemical volatile stimuli. However, development of the psyllid in relation to the ontogeny of immature citrus flush growth has not been clearly defined or illustrated. Such information is important for determining the timing and frequency of measures used to minimize populations of the psyllid in orchards and spread of HLB. Our objective was to study how flush ontogeny influences the biotic potential of the psyllid. We divided citrus flush growth into six stages within four developmental phases: emergence (V1), development (V2 and V3), maturation (V4 and V5), and dormancy (V6). <i>Diaphorina citri</i> oviposition and nymph development were assessed on all flush stages in a temperature controlled room, and in a screen-house in which ambient temperatures varied. Our results show that biotic potential of <i>Diaphorina citri</i> is not a matter of the size or the age of the flushes (days after budbreak), but the developmental stage within its ontogeny. Females laid eggs on flush V1 to V5 only, with the time needed to commence oviposition increasing with the increasing in flush age. Stages V1, V2 and V3 were most suitable for oviposition, nymph survival and development, and adult emergence, which showed evidence of protandry. Flush shoots at emerging and developmental phases should be the focus of any chemical or biological control strategy to reduce the biotic potential of <i>D</i>. <i>citri</i>, to protect citrus tree from Liberibacter infection and to minimize HLB dissemination.</p></div