Patents Medical devices using gels Applicanthventor: J.H. Lemelson (USA)

This patent describes a self-propelled drug delivery

device responsive to an applied voltage, having a

drug delivery container. The drug dose is sealed in

a flexible sack surrounded by a layer of expandable

copolymer gel. The gel, enclosed in a permeable

membrane, is coupled to an electrode which

applies a voltage, causing controllable contraction

of the copolymer gel to release the drug.

Electrically actuated copolymer gel can also

provide a means of propulsion: the drug-delivery

unit is attached to a flexible propulsion unit with

two compartments separated by a septum. The

first compartment contains a flexible, inert filler,

the second an expandable copolymer gel enclosed

in a permeable membrane. Application of a

voltage to the gel in the propulsion unit by a

second electrode results in flexing of the container

and motion of the whole device through a

surrounding fluid medium or passage.

Patent number: US 6287294

Publication dute: 11 September 2001

Ceramics properties Applicant: National Institute of Advanced

Industrial Science & Technology, Japan

This provides novel ceramic materials with

excellent electrostrictive properties. The material

consists of a solid-solution ceramic obtained by

combining 2634 mol% of primitive perovskite-

type compound PbTiO, with a composite

perovskite compound Pb(Ni,,3Nb,,,)0,. This

is produced by wet mixing lead oxide, nickel

oxide, niobium oxide and titanium oxide,

forming the mixture into a tablet. Heat treated at

800-1000°C in air, any unreacted product

dissolves out using 1M acetic acid. Particles of

the material are finally sintered in a PbO

atmosphere at 1270°C. Ceramic actuators from

this material show displacement several times

larger than that of Pb(Mg,,,Nb,,$-PbTiO,

solid solutions, being tested for use as

electrostrictive actuators. Theoretically, electro-

strictive ceramics have little hysteresis and

change over time in strain compared with

piezoelectric ceramics. Applications can be

expected where piezoelectric ceramic actuators

have been used, and high accuracy and precise

control of displacement are required.

Patent number: US 6288002

Publication date: 11 September 2001

Inventors: K. Kusumoto, T. Sekiya

Magnetostrictive actuating device Applicant: Cetus Innovation AB, Sweden

This invenrion refers to a magnetostrictive

actuating device provided with at least one

channel for a cooling medium. The actuating

device comprises an elongated rod of a

magnetostrictive material, a magnetic coil

arranged around the rod, a permanent magnet

member adapted to magnetize the rod together

with the coil, and a magnetic return conductor

member. The components form a closed magnet

circuit. There is at least one cooling channel

adapted to conduct a cooling medium for

cooling the actuating device. This comprises an

inlet and outlet sections and an intermediate

section, in which the inlet and/or outlet sections

extend at least partly into the permanent magnet

member.

Patent number: WO 01167432

Publication date: 13 September 200 1

Inventor: G.R. Engdahl

Magnetorheological damper

charging system Applicant: Delphi Technologies, USA

This improved magnetorheological (MR)

damper charging system simply and

substantially minimizes leakage of MR fluid

during the process of assembling the damper.

The damper charging system includes a

charging body having a bore for receiving

damper components and damper fluid, and at

least one inlet formed in the charging body for

delivering fluid to the bore. An assembly to

generate a magnetic field is mounted at the

inlet and operates in an energized state to

generate a magnetic field across the inlet. This

causes MR fluid in the inlet to experience an

MR effect sufficient to prevent leakage flow

through and from the inlet. An inlet valve is

mounted on the charging body to control flow

of fluid through the inlet into the bore. A

conventional damper charging assembly in-

cludes a charging tube and a set of fill holes and

valves for controlling MR fluid flow through

the holes. MR fluid leakage can occur in

the gap around the valve and corresponding

hole during movement of the components

from the charging assembly into the damper

cylinder. This can accumulate, resulting in

unacceptable, expensive MR fluid usage and

increased clean-up costs. In the present

invention magnetic flux is generated within

a clearance gap between the valve and the

inlet walls, blocking flow and preventing

leakage.Clean-up is minimized, cost reduced.

Patent number: US 6290033

Publication date: 18 September 200 1

Inventor: M.L. Oliver

Vibration absorber using SMA Applicant: Purdue Research Foundation, USA

This patent relates to an adaptive-passive

vibration absorber using a shape memory alloy.

A vibration-absorbing end or ‘tuning’ mass, is

coupled to the primary mass (subject to

unwanted vibration) by means of a cantilevered

beam. At least a portion of the beam is made

from the SMA. Preferably, the end mass is also

coupled to the primary mass with several

discrete SMA wires which may be individually

heated by passing electric current through

them. When each of the SMA wires is heated

above a predetermined temperature, it under-

goes a phase change, which results in a change

in the stiffness of the wire. Heating various

wires in different combinations allows the

operational frequency of the absorber end mass

to be actively tuned. The frequency of the

absorber may be adaptively tuned, in a simple

manner, to closely match the vibrational

frequency of the primary mass.

Patent number: US 6290037

Publication d&e: 18 September 2001

Inventors: K.A. Williams, G.T. Chiu, R.J.

Bernhard

Tungsten coating for MEMS

Applicant: Sandia Corporation, USA

This method for coating semiconductor surfaces

within a microelectromechanical) device with

tungsten to improve wear resistance and

reliability of moving parts, such as gears. The

semiconductor surfaces ( silicon, germanium or

silicon carbide) are cleaned to remove organic

material and oxide film from the surface. A final

in situ cleaning step is performed by heating a

substrate containing the MEMS device to a

temperature in the range 200-600°C in the

presence of gaseous nitrogen trifluoride (NF3).

The tungsten coating can be formed by a

chemical reaction between semiconductor

surfaces and tungsten hexafluoride (WFG) at an

elevated temperature, preferably about 450°C.

Tungsten deposition is self-limiting, covering all

exposed semiconductor surfaces, including those

in close contact, with a conformal coating of

controlled thickness between 5-50 nm. Wear is a

significant failure and reliability issue for MEMS

devices, especially for load-bearing or rubbing

surfaces. The presence of the tungsten coating is

claimed to provide substantial improvement in

such devices. The coating is compatible with

conventional IC process technology and can be

applied to many devices, including microrelays,

micromirrors and microengines. Ir is claimed

that the coating can be used to enhance the

hardness, conductivity, optical reflectivity and

chemical inertness of one or more semi-

conductor surface within a MEMS device.

Patent number: US 6290859

Publication date:1 8September 200 1

Inventors: J.G. Fleming, S.S. Mani, J.J.

Sniegowski, R.S. Blewer

Smart Materials Bulletin January 2002