Biologically inspired microtexturing: investigation into the surface topography of next-generation neurosurgical probes.

Minimally Invasive (MI) surgery represents the future of many types of medical intervention (keyhole neurosurgery, natural orifice trans-luminal endoscopic surgery, etc.). However, the shortcomings of today's surgical tools fuel the need for the development of next-generation 'smart instrumentation', which will be more accurate and safer for the patient. This paper presents the preliminary results of a biologically inspired microtexturing method, based on UV-lithography, and its application to MI neurosurgery. These results suggest that the size and geometry of the texture 'printed' on the outer surface of a neurosurgical probe clearly affect the insertion and extraction forces generated at the brain-probe interface. Thus, by carefully choosing an appropriate microtexture, unique insertion characteristics can be obtained, which can improve the performance of existing instruments (e.g. reducing slippage in permanent electrodes such as those used in deep brain stimulation) or enable the development of novel designs altogether.

Mechanism responsible for initiating carbon nanotube vacuum breakdown.

We report a physical mechanism responsible for initiating a vacuum breakdown process of a single carbon nanotube (CNT) during field emission. A quasidynamic method has been developed to simulate the breakdown process and calculate the critical field, critical emission current density and critical temperature beyond which thermal runaway occurs before the CNT temperature reaches its melting point. This model is in good agreement with experiments carried out with a single CNT on a silicon microtip.

Microfabrication and characterization of gated amorphous diamond-based field emission electron sources.

Gated field emission electron sources of amorphous diamond (a-D) coated Si tips and a-D diodes on a rough Si substrate were studied, detailing the deposition and characterization of the thin film, the fabrication processes and the emission behavior of the electron sources. Mechanisms responsible for the emission process of the a-D coated devices are proposed. A comparison of the field emission performance of the two types of devices is presented. In addition, future improvements of the a-D diode on a rough Si cathode are discussed.