Heat-activated drug delivery system and thermal actuators therefor
First Claim
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1. A linear motor comprising:
- a) a thermal actuator, said actuator including;
i) an actuator body defining a chamber and having opposite ends,ii) a force-transmitting elastomeric component disposed in said chamber, said elastomeric component being closed at one end and having a central bore of predetermined diameter through the opposite end, said elastomeric component having a wall of predetermined thickness and of a predetermined durometer rating, said actuator body including an annular wall encircling said elastomeric component in spaced relation thereto,iii) an actuation rod having an end portion reciprocably received in said bore, andiv) a thermally responsive expansion material contained between said elastomeric component and said encircling wall for squeezing said elastomeric component to force said actuation rod outwardly of said chamber; and
b) heating means for causing said thermally responsive expansion material to expand, thereby producing linear motion from said actuation rod.
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Abstract
A thermal actuator, also known as a heat capacitance motor, derives its energy from the physical expansion of paraffin wax as it changes from solid to liquid when heated within an enclosure such as a cylinder. This energy is converted into mechanical force which causes translation of a piston slidably mounted within the cylinder, thus creating hydrostatic pressure which is converted to work. The thermal actuator may be utilized in various drug delivery systems in which the hydrostatic pressure created by the actuator is used expel the contents of a syringe.
71 Citations
13 Claims
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1. A linear motor comprising:
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a) a thermal actuator, said actuator including; i) an actuator body defining a chamber and having opposite ends, ii) a force-transmitting elastomeric component disposed in said chamber, said elastomeric component being closed at one end and having a central bore of predetermined diameter through the opposite end, said elastomeric component having a wall of predetermined thickness and of a predetermined durometer rating, said actuator body including an annular wall encircling said elastomeric component in spaced relation thereto, iii) an actuation rod having an end portion reciprocably received in said bore, and iv) a thermally responsive expansion material contained between said elastomeric component and said encircling wall for squeezing said elastomeric component to force said actuation rod outwardly of said chamber; and b) heating means for causing said thermally responsive expansion material to expand, thereby producing linear motion from said actuation rod. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification