A catheter suitable for directing a measured aliquot of liquid drug to a specific target location in the body having a reservoir containing a premeasured aliquot of liquid drug which is positioned near the end of catheter. The reservoir is attached to the distal end of an extendable member, which is used to extend the hollow needle into the tissue surrounding the distal end of the catheter through an orifice.

System and method for treating select tissue in a living being

The spherical, monodisperse polymer microshperes (PAPMMAs) consisting of a poly(methyl methacrylate) (PMMA) core and a polyaniline (PANI) shell were prepared and adopted as dispersed materials for electrorheological (ER) fluids, in which electrical conductivity was originated primarily from the surface-coated conducting PANI layer. These surfaces were rough and irregular. Three different core sizes of PAPMMAs (2, 4.5, and 9 μm) with the same weight ratio of PANI, the larger core having the thicker PANI shell, were prepared. PAPMMAs that have similar shell thicknesses but different core sizes were also prepared in order to examine the particle size effect on ER performance. Performances of PAPMMA-based ER fluids were enhanced with increasing core particle size. The same result was obtained for the PAPMMA systems having the same shell thickness. Dielectric spectra of these ER fluids were found to provide additional information on both analyzing their electrical polarization properties and interpreting the f...

Synthesis and electrorheological characteristics of polyaniline-coated poly(methyl methacrylate) microsphere: Size effect

An intelligent material unit formed of an intelligent gel encapsulated within an enclosure. When the gel is actuated by a change in temperature thereof, such as heat and/or by an externally applied field such as an electrical current, electric field, magnetic field, ultrasonic energy (or sonic), microwave energy, a laser beam or a combination thereof, at least a portion of the wall of the container or enclosure is deformed to perform a mechanical function or operation; such as to valve a fluid or cause movement of the container and gel through a fluid or in a passageway. The container may be a thin-skinned flexible plastic, such as an elastomer and may be elongated or sausage-like in shape, or strip-like. It may be free travelling, cantilever-supported or otherwise mounted or attached to a device, machine or element. It may also carry a drug for delivery therefrom at a select location and time. A system apparatus and method is also disclosed for delivering a quantity of a drug, tissue, cells, genetic material, sensor, implant or implant material, repair material, diagnostic material, protein, hormone or the like or a combination thereof to a select location in the body, such as in an artery, vein, or a portion of the digestive tract. In one form, a select amount of such a (medical) material is disposed within a so-called intelligent gel per se or in one or more small capsules or the like in or attached to such intelligent gel or a container therefor, such as a thin skinned flexible elongated balloon-like enclosure. Such elongated, narrow container or strip of electrical energy or magnetic or radio-frequency energy force responsive gel attached to or containing medical material, is inserted into a body duct such as a vein or artery and is caused to "swim" or wiggle therealong to a select location therein by passing electrical energy through the blood (and vessel wall) and/or by means of an alternating magnetic or radio-frequency field controllably applied thereto with a hand-held instrument which is moved by hand to induce such movement and/or controllably may move such field in a manner to induce the gel to move or swim to the select location. In a particular form, the drug and gel are small enough in size to pass into the bloodstream through the wall of the small intestine after being swallowed, as a drug unit along with other such drug units--when so located at the select location in the body duct, the drug carried by the intelligent gel or (sausage-like) membrane or thin skin contained unit is released therefrom by biodegradation or other means, such as by radio-frequency, ultrasonic or magnetic field energy applied from outside the body or a catheter, or a combination thereof.

Medical devices using electrosensitive gels

An electrorheological fluid, a special type of suspension with controllable fluidity by an electric field, generally contains semiconducting or polarizable materials as electro-responsive parts. These materials align in the direction of the applied electric field to generate a solid-like phase in the suspension. These electro-responsive smart materials, including dielectric inorganics, semiconducting polymers and their hybrids, and polymer/inorganic composites, are reviewed in terms of their mechanism, rheological analysis and dielectric characteristics.

Electrorheological fluids: smart soft matter and characteristics

The conductive, dielectric, and surface properties of several water-free polymer or inorganic material based ER fluids, as well as their response times, are investigated to elucidate the physical ground of the electrorheological (ER) effect. It is found that the slow polarization, especially the interfacial polarization rather than the Debye polarization, might be responsible for the observed phenomena. A possible ER mechanism is proposed as follows:  a large interfacial polarization would facilitate the particle to attain a large amount of charges on the surface, then leading to the turn of particle along the direction of an electric field to form a fibrillation structure; the strength of fibrillation chains is thus determined by the particle polarization force, i.e., the particle dielectric constant. The rationality that the marked interfacial polarization would likely drive the particles to turn is theoretically addressed on the basis of experimental results.

Mechanism of the Electrorheological Effect: Evidence from the Conductive, Dielectric, and Surface Characteristics of Water-Free Electrorheological Fluids

We have carried out a set of experiments using anhydrous carbonaceous particles to determine the effect on the electrorheological properties of blending particles of different conductivities. We find that there is a significant dip in the shear stress under an electric field as the concentration of higher conductivity particles is increased, showing that uniformity of the electrical properties among the particles is a most important factor in achieving optimum electrorheological fluid (ERF) performance. We explain this behavior by a simple model based on the strength of particle–particle interactions. Measurements of the dielectric permittivity show that the α parameter of the Cole–Cole expression provides an excellent way to express the degree of uniformity in the electrical properties. This gives a convenient method to evaluate the potential performance of an ERF.

The effect of blending particles with different conductivity on electrorheological properties

The present invention can provide particles for electro-rheological fluid for providing a high electro-rheological effect over a wide temperature range at low electric power consumption, and having high strength and excellent durability, not being susceptible to break-up due to the load of stress. Particles for an electro-rheological fluid of the present invention comprise spherical carbonaceous particles, obtained substantially from a solvent and a condensation product of a methylene type bond of aromatic sulfonic acid or a salt thereof.

Particles for electro-rheological fluid

An electro-responsive elastomeric material comprising (A) an electrically insulating polymer having a specific modulus of elasticity and (B) a fine powder dispersed in the polymer which electrically polarizes under an electric field independent of water changes its viscoelasticity upon voltage application. The powder has a mean particle size of 0.5 to 500 µm and is (1) a fine carbonaceous powder having a C/H atomic ratio of from 1.2 to 5, (2) composite particles having minute particulates of an insulating material dispersed in a matrix phase of a carbonaceous or carbide material, (3) composite particles having minute particulates of a carbonaceous or carbide material dispersed in a matrix phase of an insulating material, or (4) a fine composite powder of a stratum clay mineral having a two-dimensional stratum structure with a carbonaceous or carbide material incorporated between the strata.

Electro-responsive elastomeric materials

A positive electrode and a negative electrode are disposed in face-to-face relation to allow a distance between the electrodes to change, and an electrorheological fluid is filled between the electrodes. When an external force is applied to the electrorheological fluid via the electrodes, a normal stress occurs in the electrorheological fluid. This normal stress is greater than a shearing stress occurring in the electrorheological fluid, and an area in which displacement is proportional to the stress is large. Hence, the electrorheological fluid is applicable to various apparatuses such as a vibration controller and a fixing apparatus.

Electrorheological fluid-applied apparatus, electrorheological fluid-applied vibration controller, and electrorheological fluid-applied fixing apparatus

A comparison is made between two types of solid particles used in electrorheological fluids: particles with homogeneous electrical properties versus layered particles with a semi-conducting core surrounded by an outer layer of lower conductivity. Rheological measurements of these suspensions under steady shear and d.c. electric field show that the layered particle system produces the same yield stress but with a substantially reduced electric current. X-ray spectroscopic analysis confirms that these particles have a thin layer of SiOx on the outer surface which causes the reduction in conductivity. Measurement of the dielectric permittivity followed by analysis using the Maxwell-Wagner model of polarization indicates that the conductivity of the outer layer is about 0.62 times that of the core region.

Tasuku Saito

Papers

The effect of blending particles with different conductivity on electrorheological properties

Particles for electro-rheological fluid

Electro-responsive elastomeric materials

Electrorheological fluid-applied apparatus, electrorheological fluid-applied vibration controller, and electrorheological fluid-applied fixing apparatus

Suspension of layered particles: an optimum electrorheological fluid for d.c. applications