6.4 GHz Acoustic Sensor for In-situ Monitoring of AFM Tip Wear

This paper demonstrates an acoustic sensor that can resolve atomic force microscopy (AFM) tip blunting with a frequency sensitivity of 0.007%. The AFM tip is fabricated on a thin film piezoelectric aluminum nitride (AlN) membrane that is excited as a film bulk acoustic resonator (FBAR). We demonstrate that cutting 0.98 μm off of the tip apex results in a resonance frequency change of 0.4MHz at 6.387GHz. This work demonstrates the potential for in-situ monitoring of AFM tip wear

Nano-electromechanical Zero-dimensional Freestanding Nanogap Actuator

Micromachined free standing nanogap with metal electrodes is presented. The gap size is as small as 17 nm, and can be reduced further with electrostatic or piezoelectric actuation. The nanoscale gap is fabricated by industrial standard optical lithography and anisotropic wet chemical Si etching. Electron transport between the metal electrodes with optical stimulus enhancing photon-electron coupling (plasmon) is presented

Plasticidade do sistema auditivo Auditory system plasticity

O sistema sensorial auditivo tem sido alvo de estudos sobre sua capacidade de desenvolver respostas plásticas a diferentes tipos de lesão. Fenômenos regenerativos se fazem observar no segmento periférico do sistema, com a constatação da neogênese de células ciliadas em aves, em alguns casos acompanhada de recuperação funcional comprovada eletrofisiologicamente. Alterações em estruturas centrais da via auditiva, secundárias a uma lesão do órgão periférico, têm sido freqüentemente relatadas, significando uma provável resposta plástica à perturbação do sinal aferente. Exemplo extremo dessas alterações é encontrado em roedores que desenvolvem, secundariamente à indução de perda auditiva parcial, comportamento motor anômalo em resposta ao som intenso, denominado epilepsia audiogênica. Os autores fazem uma revisão sobre o assunto.<br>The auditory system has been subject of studies that evaluated its capability to develop plastic responses to different kinds of lesions. Regeneration has been observed in the peripheral portions of the system, with neogenesis of the hair cells in avian, sometimes followed by functional rehabilitation as confirmed by electrophysiological testing. The occurrence of central auditory pathway disorders, secondary to peripheral damage, has been frequently noticed, probably due to a plastic reaction to the lack of afferent signal. A great example of these alterations is found in rodents that develop anomalous motor response to loud sounds, secondary to induced partial deafness, named audiogenic seizures. The authors presented a review about the theme