New and efficient design of multimode piezoelectric vibration energy harvester for MEMS application

The major challenges in a piezoelectric energy harvester (PEH) are high operating frequency, narrow bandwidth and low output generation. We propose a new and efficient design concept based on optimal geometry shape and optimal segmentation of piezoelectric layer at strain nodes of higher vibration modes. The analytical model of the proposed design concept is developed and comparative analysis is performed to compare with conventional rectangular PEH and non-segmented trapezoidal PEH. For a mode 3 harvester design, the simulation result shows that there are three resonant peaks for voltage generation, at the fundamental, 2nd and 3rd resonant frequencies to enable multi-frequency operation that widens the operating frequency range of PEH. The parallel connection of the piezoelectric PZT segments to a common load resistance yields 21.6 mW, 0.23 mW and 0.15 mW power output for three resonant frequencies at 0.5 g input acceleration for optimal load of 21 kΩ. The proposed device shows a performance improvement and reduction in operating resonating frequencies of the higher modes of vibration compared to conventional rectangular and a non-segmented trapezoidal shaped PEH. The harvester provides an alternative to complex and inefficient device design of multimodal energy harvesters

Transcriptional and functional profiles of voltage-gated Na(+) channels in injured and non-injured DRG neurons in the SNI model of neuropathic pain.

Changes in expression and function of voltage-gated sodium channels (VGSC) in dorsal root ganglion (DRG) neurons may play a major role in the genesis of peripheral hyperexcitability that occurs in neuropathic pain. We present here the first description of changes induced by spared nerve injury (SNI) to Na(v)1 mRNA levels and tetrodotoxin-sensitive and -resistant (TTX-S/TTX-R) Na(+) currents in injured and adjacent non-injured small DRG neurons. VGSC transcripts were down-regulated in injured neurons except for Na(v)1.3, which increased, while they were either unchanged or increased in non-injured neurons. TTX-R current densities were reduced in injured neurons and the voltage dependence of steady-state inactivation for TTX-R was positively shifted in injured and non-injured neurons. TTX-S current densities were not affected by SNI, while the rate of recovery from inactivation was accelerated in injured neurons. Our results describe altered neuronal electrogenesis following SNI that is likely induced by a complex regulation of VGSCs

TReND in Africa: toward a truly global (neuro)science community

TReND is a volunteer-scientist run charity dedicated to promoting research and education on the African continent. Focusing on neuroscience, we discuss approaches to address some of the factors that currently stifle Africa’s scientific development and our experience in implementing them