Multiple tip arrays

In this paper we present a comprehensive experimental and theoretical description of nanodomain reversal in fe bulk crystals an experimental method for domain switching using hvafm, results on nanodomain switching using hvafm and under indirect electron beam exposure, theory of fe domain breakdown and our last development of the fabrication of nanodomain gratings by the use of multiple tip arrays. We show that fdb is a new physical phenomenon observed in bulk fe crystals, and is the basis for the development of nanodomain technology in bulk fe crystals. This technology is required for future photonic, acoustic and microelectronic devices. 

Nanodomain superlattices tailored by multiple tip arrays of hvafm... 

In this chapter we report about the use of multiple afm tip array for parallel domain writing in bulk fe crystals. Fabrication of nanodomain gratings is based on direct writing of nanodomains with small ratio r/l < 10 - - 10 It is shown that the only mechanism providing such a low ratio is the fdb effect [13-15]. 

Figure 10.14 (a) Periodic domain structure tailored in a RbTiOAsC>4 single crystal by moving the multiple HVAFM tip arrays along the Y-axis direction with a velocity of 120 pm/sec. (b) The insert of a periodic domain structure written by one tip of the arrays. 

Figure 10.15 Schematic diagram describing the calculation of the electric field generated by the multiple hvafm tip arrays.

Two key issues in SECM are speed and resolution. These are tied to the nature of the available tips and the techniques used to move them in the vicinity of the sample. One approach to greater speed is the use of multiple tips. There are a number of approaches to the fabrication of an array of tips. A problem with these arrays is alignment of the array with the sample so that all of the tips are at the same or a known distance from the sample. This can be accomplished by having each tip on its own controllable positioning device, such as an array of cantilevers with individual piezoelectric control (32,33). For example, 50 cantilevers with a 200-/xm period (to cover a span of 1 cm) were fabricated with integrated piezo sensors and zinc oxide actuators. Such an array provided 35 A resolution and a 20 kHz bandwidth. A difficulty with such arrays is the complexity of the instrumentation needed to use them. Each sensor in the array essentially needs its own driver and potentiostat. An alternative would be an array of individually addressable tips on a single chip that all move in the x, y, and z directions in unison. This would require some additional means to orient and align the array chip... 

The tail of the plasma formed at the tip of the torch is the spectroscopic source, where the analyte atoms and their ions are thermally ionized and produce emission spectra. The spectra of various elements are detected either sequentially or simultaneously. The optical system of a sequential instrument consists of a single grating spectrometer with a scanning monochromator that provides the sequential detection of the emission spectra lines. Simultaneous optical systems use multichannel detectors and diode arrays that allow the monitoring of multiple emission lines. Sequential instruments have a greater wavelength selection, while simultaneous ones have a better sample throughput. The intensities of each element s characteristic spectral lines, which are proportional to the number of element s atoms, are recorded, and the concentrations are calculated with reference to a calibration standard. 

There are two formats of microarray oligonucleotide chips contain short (less than 60) nucleotides synthesized in situ on the solid support (1,2) and spotted DNA arrays where nucleic acids are robotically spotted onto a glass substrate (3). PCR product or plasmid DNA in 96/384-well format is transferred by specially engineered tips to multiple glass slides then dried and fixed to the glass substrate. 

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