Resonance Frequency Selective Electromagnetic Actuation for High-Resolution Vibrotactile Displays

Vibrotactile displays offer significant potential for conveying information through the sense of touch in a wide variety of applications. Spatial resolution of these displays is limited by the large size of actuators. We present a new selective electromagnetic actuation technique to control the vibrations of multiple tactile elements using a single coil based on their individual mechanical resonance frequencies. This technique allows low-cost and highly reliable implementation of many tactile elements on a smaller area. A prototype is manufactured using 3D-printed tactile elements and off-the-shelf coils to characterize the proposed technique. This prototype successfully increases the resolution by 100 % from 16 to 32 tactile pixels (taxels) on a 25 cm2 pad, without sacrificing other performance metrics such as refresh rates and power consumption. The multiphysics finite element analysis developed for this new actuation technique are experimentally validated by optical vibrometry measurements. This work demonstrates the capability of resonance-selective electromagnetic actuator in developing high-resolution low-cost vibrotactile displays

Asymmetric Quad-Leg Orthoplanar Spring For Wideband Piezoelectric Micro-Energy Harvesting

Piezoelectric energy harvesters (EH) generate their highest energy levels at the resonant frequencies of the transducer devices. To provide a wide-band EH solution, nonlinear mechanical resonators with multiple resonant modes can be used. We present a new asymmetric quad-leg orthoplanar spring (QOPS) EH microstructure to increase the harvesting bandwidth. The proposed design is implemented in CMOS compatible microfabrication processes. Finite element analysis show that the asymmetric designs increases the bandwidth by maximum 27% compared with symmetric designs. In order to measure the electrical output, one symmetric and three asymmetric piezoelectric devices implemented on the same microchip are exposed to mechanical vibrations over a wide frequency bandwidth. Experimental results approve the increase in the frequency bandwidth of resonators introduced by asymmetries added to the spring, as compared to the symmetrical configuration. © 2023 IEEE.<br/

Asymmetric Quad-Leg Orthoplanar Spring For Wideband Piezoelectric Micro-Energy Harvesting

Piezoelectric energy harvesters (EH) generate their highest energy levels at the resonant frequencies of the transducer devices. To provide a wide-band EH solution, nonlinear mechanical resonators with multiple resonant modes can be used. We present a new asymmetric quad-leg orthoplanar spring (QOPS) EH microstructure to increase the harvesting bandwidth. The proposed design is implemented in CMOS compatible microfabrication processes. Finite element analysis show that the asymmetric designs increases the bandwidth by maximum 27% compared with symmetric designs. In order to measure the electrical output, one symmetric and three asymmetric piezoelectric devices implemented on the same microchip are exposed to mechanical vibrations over a wide frequency bandwidth. Experimental results approve the increase in the frequency bandwidth of resonators introduced by asymmetries added to the spring, as compared to the symmetrical configuration. © 2023 IEEE.<br/

Time Domain Multiplexing for Efficiency Enhanced Piezoelectric Energy Harvesting in MEMS

The conversion efficiency of piezoelectric energy harvesters (EH) have been improved by several approaches including frequency up-conversion (FUC) techniques that trigger the high-frequency (HF) piezoelectric resonators using low-frequency (LF) mechanical inputs. This work proposes a new time-domain multiplexing technique to further improve the harvesting efficiency for random mechanical impacts using commercially available microfabrication processes. The FUC is implemented by a slowly moving shuttle beam, which represents the LF mechanical inputs, that triggers the free ends of piezoelectric cantilever beams. Mechanical impacts by the LF shuttle lead to the cantilever beams vibrating at their higher natural resonance frequencies. In the proposed approach, resonators are exposed to the LF mechanical input at unequal distances, which results in sequential HF vibrations. As a result, the HF electrical outputs fit sequentially within the long period of the LF input. Analytical and experimental comparisons support the increased electrical output using time domain multiplexing.</p

The Design of a Low Noise, Multi-Channel Recording System for Use in Implanted Peripheral Nerve Interfaces

In the development of implantable neural interfaces, the recording of signals from the peripheral nerves is a major challenge. Since the interference from outside the body, other biopotentials, and even random noise can be orders of magnitude larger than the neural signals, a filter network to attenuate the noise and interference is necessary. However, these networks may drastically affect the system performance, especially in recording systems with multiple electrode cuffs (MECs), where a higher number of electrodes leads to complicated circuits. This paper introduces formal analyses of the performance of two commonly used filter networks. To achieve a manageable set of design equations, the state equations of the complete system are simplified. The derived equations help the designer in the task of creating an interface network for specific applications. The noise, crosstalk and common-mode rejection ratio (CMRR) of the recording system are computed as a function of electrode impedance, filter component values and amplifier specifications. The effect of electrode mismatches as an inherent part of any multi-electrode system is also discussed, using measured data taken from a MEC implanted in a sheep. The accuracy of these analyses is then verified by simulations of the complete system. The results indicate good agreement between analytic equations and simulations. This work highlights the critical importance of understanding the effect of interface circuits on the performance of neural recording systems

The Design of a Low Noise, Multi-Channel Recording System for Use in Implanted Peripheral Nerve Interfaces

In the development of implantable neural interfaces, the recording of signals from the peripheral nerves is a major challenge. Since the interference from outside the body, other biopotentials, and even random noise can be orders of magnitude larger than the neural signals, a filter network to attenuate the noise and interference is necessary. However, these networks may drastically affect the system performance, especially in recording systems with multiple electrode cuffs (MECs), where a higher number of electrodes leads to complicated circuits. This paper introduces formal analyses of the performance of two commonly used filter networks. To achieve a manageable set of design equations, the state equations of the complete system are simplified. The derived equations help the designer in the task of creating an interface network for specific applications. The noise, crosstalk and common-mode rejection ratio (CMRR) of the recording system are computed as a function of electrode impedance, filter component values and amplifier specifications. The effect of electrode mismatches as an inherent part of any multi-electrode system is also discussed, using measured data taken from a MEC implanted in a sheep. The accuracy of these analyses is then verified by simulations of the complete system. The results indicate good agreement between analytic equations and simulations. This work highlights the critical importance of understanding the effect of interface circuits on the performance of neural recording systems