Enabling closed-loop neural interface: A bi-directional interface circuit with stimulation artifact cancellation and cross-channel CM noise suppression

In this paper, the Enhanced Active Constrained Layer (EACL) treatment is investigated for broadband damping augmentations on beam structures. The EACL concept was originally proposed to improve the damping performance of the Active Constrained Layer (ACL) by introducing edge elements at the treatment boundaries. It has been recognized that the edge elements can increase ACL performance by enhancing the direct active authority of the piezoelectric constraining layer. It has also been demonstrated that the edge element stiffness and the host structure strain field have significant influence on the overall closed-loop system damping and its various components: the active damping, the closed-loop passive damping, and the open-loop passive (fail-safe property - without any active action) damping. Through utilizing this finding, the present study explores how the EACL performance can be synthesized for multiple mode broadband applications using symmetric configurations. Although the edge elements will tend to reduce the maximum possible open-loop damping of one (or a few) vibration mode, open-loop damping of the other higher order modes could actually be increased. Moreover, the modal damping reduction in the open-loop system can generally be compensated by the significant increase of the closed-loop damping. In other words, the closed-loop EACL system damping over a wide frequency range can be significant, which makes it attractive for broadband vibration and noise suppression.

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Study of a closed-loop high-precision front-end circuit for tunneling magneto-resistance sensors

Modern Physics Letters B ◽

10.1142/s0217984919500854 ◽

2019 ◽

Vol 33 (08) ◽

pp. 1950085 ◽

Cited By ~ 4

Author(s):

Xiangyu Li ◽

Jianping Hu ◽

Xiaowei Liu

Keyword(s):

High Precision ◽

Closed Loop ◽

Low Frequency ◽

Cmos Technology ◽

Low Noise ◽

Corner Frequency ◽

Cmos Process ◽

Interface Circuit ◽

Front End ◽

Magneto Resistance

A closed-loop high-precision front-end interface circuit in a standard 0.35 [Formula: see text]m CMOS technology for a tunneling magneto-resistance (TMR) sensor is presented in this paper. In consideration of processing a low frequency and weak geomagnetic signal, a low-noise front-end detection circuit is proposed with chopper technique to eliminate the 1/f noise and offset of operational amplifier. A novel ripple suppression loop is proposed for eliminating the ripple in a tunneling magneto-resistance sensor interface circuit. Even harmonics is eliminated by fully differential structure. The interface is fabricated in a standard 0.35 [Formula: see text]m CMOS process and the active circuit area is about [Formula: see text]. The interface chip consumes 7 mW at a 5 V supply and the 1/f noise corner frequency is lower than 1 Hz. The interface circuit of TMR sensors can achieve a better noise level of [Formula: see text]. The ripple can be suppressed to less than 10 [Formula: see text]V by ripple suppression loop.

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Piezoelectric MEMS Resonators for Cigarette Particle Detection

Micromachines ◽

10.3390/mi10020145 ◽

2019 ◽

Vol 10 (2) ◽

pp. 145 ◽

Cited By ~ 9

Author(s):

Javier Toledo ◽

Víctor Ruiz-Díez ◽

Maik Bertke ◽

Hutomo Suryo Wasisto ◽

Erwin Peiner ◽

...

Keyword(s):

Resonance Frequency ◽

Closed Loop ◽

Low Cost ◽

Open Loop ◽

Piezoelectric Resonator ◽

Particle Detection ◽

Interface Circuit ◽

Mems Resonators ◽

Loading Effects ◽

Working Principle

In this work, we demonstrate the potential of a piezoelectric resonator for developing a low-cost sensor system to detect microscopic particles in real-time, which can be present in a wide variety of environments and workplaces. The sensor working principle is based on the resonance frequency shift caused by particles collected on the resonator surface. To test the sensor sensitivity obtained from mass-loading effects, an Aluminum Nitride-based piezoelectric resonator was exposed to cigarette particles in a sealed chamber. In order to determine the resonance parameters of interest, an interface circuit was implemented and included within both open-loop and closed-loop schemes for comparison. The system was capable of tracking the resonance frequency with a mass sensitivity of 8.8 Hz/ng. Although the tests shown here were proven by collecting particles from a cigarette, the results obtained in this application may have interest and can be extended towards other applications, such as monitoring of nanoparticles in a workplace environment.

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