Invasive temperature devices

Another problem in the construction of tlrese devices, is that materials which do not play a direct part in the operation of the microchip must be introduced to ensure electrical contact between the elecuonic components, and to reduce the possibility of chemical interactions between the device components. The introduction of such materials usually requires an annealing phase in the construction of die device at a temperature as high as 600 K. As a result it is also most probable, especially in the case of the aluminium-silicon interface, that thin films of oxide exist between the various deposited films. Such a layer will act as a banier to inter-diffusion between the layers, and the transport of atoms from one layer to the next will be less than would be indicated by the chemical potential driving force. At pinholes in the AI2O3 layer, aluminium metal can reduce SiOa at isolated spots, and form the pits into the silicon which were observed in early devices. The introduction of a tlrin layer of platinum silicide between the silicon and aluminium layers reduces the pit formation. However, aluminium has a strong affinity for platinum, and so a layer of clrromium is placed between the silicide and aluminium to reduce the invasive interaction of aluminium. 

MRI-guided focused ultrasound fibroid ablation is the newest of the non-invasive techniques and is still in the experimental stages. The ultrasound waves are directed from a transducer into a small focal volume. The tissue at the focal point receives condensed energy and increases in temperature, causing protein denaturation, cell death and coagu-lative necrosis. While a commercial device is available, long term data on this procedure does not yet exist [45]. 

SMPs have most notably been promoted because of their potential in minimally invasive surgery, where a compacted device could be passed through a smaller incision and deployed to its full shape once inside the body [40]. For biomedical devices, the heating of polymer to activate SMEs has been proposed by body, temperature, optical/laser heating, and remote inductive heating [41]. As each of these thermal activation methods is possible within the body, control over SMP geometry is possible with implantable devices. 

Need of multifunctionality and to minimise invasive surgery should contribute to the development of intelligent or smart biomaterials in future which are able to respond to light, temperature, pH, etc. In this regard, PTMC-based terpolymers with shape memory properties present great interest for potential apphcations. Moreover, the development of new processing techniques, in particular computer-assisted 3D printing, makes it possible to achieve devices or scaffolds with complex architectures such as coronary stents or atrial septal defect occluders. 

The emerging role of micro- and nanoscale hot-wire anemometry would likely accelerate the translation of in vitro devices to in vivo applications, thereby bridging the lab-to-patient gap. Real-time measurements of intravascular physical parameters, specifically shear stress, temperature, pressure, and flow rate, provide a basis to link hemodynamics with biochemical events in blood vessels. The complex curvature of the vascular system requires small, minimally invasive sensors to discretely measure in real time intravascular physical parameters with minimal blood flow disturbance. To achieve this, flexible micro-and nanoscale sensors would allow for steering in the complicated anatomy in biological systems (Fig. 11). In summary, the utilization of micro- or nanoscale sensors provides a quantitative assessment of vascular hemodynamics. This approach lends itself to applications in broad areas of medicine and physiology and is particularly relevant to quantitative studies of cancer biology as well as... 

Minimally invasive surgery could reduce surgical intervention-involved complications and postsurgery costs. The shape memory properties of SMPs have made them great candidates for making devices for minimally invasive surgery. A medical device made of SMPs in an initially compressed and temporary shape could be inserted into the body through a small incision to expand on demand into its functional, permanent shape (for example, sheet, stent, and so on) at body temperature. For cardiovascular... 

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