Heat-activated drug delivery system and thermal actuators therefor
First Claim
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1. A portable drug delivery system to be worn on the body of a patient, said system comprising:
- a) a syringe having an outlet formed at one end;
b) a discharge assistant mounted for movement within said syringe, a portion of said syringe between said discharge assistant and said outlet defining a variable volume compartment for containing a drug; and
c) motive means mounted within said syringe, said motive means including a thermally responsive expansion material for creating hydraulic pressure in response to a temperature increase, actuator means for converting said hydraulic pressure to linear motion and an output shaft engaging said discharge assistant to cause said discharge assistant to move toward said outlet, expelling said drug from said variable volume compartment at a controlled rate.
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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.
115 Citations
13 Claims
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1. A portable drug delivery system to be worn on the body of a patient, said system comprising:
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a) a syringe having an outlet formed at one end; b) a discharge assistant mounted for movement within said syringe, a portion of said syringe between said discharge assistant and said outlet defining a variable volume compartment for containing a drug; and c) motive means mounted within said syringe, said motive means including a thermally responsive expansion material for creating hydraulic pressure in response to a temperature increase, actuator means for converting said hydraulic pressure to linear motion and an output shaft engaging said discharge assistant to cause said discharge assistant to move toward said outlet, expelling said drug from said variable volume compartment at a controlled rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A fluid dispensing system comprising:
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a) an enclosure defining an interior chamber and having an outlet formed at one end; b) a discharge assistant mounted for movement within said chamber, a portion of said interior chamber between said discharge assistant and said outlet defining a variable volume compartment for containing a fluid; and c) motive means mounted for movement within said enclosure, said motive means including an output shaft engaging said discharge assistant to cause said discharge assistant to move toward said outlet, expelling said fluid from said variable volume compartment, said motive means further including; a linear stepping motor, and a crawler unit for allowing said motor to move incrementally down said interior chamber, said crawler unit including; i) a cradle portion for carrying said motor, ii) a forward gripping unit configured to grip the inner surface of said enclosure when the output shaft is extended, iii) expandable and contractible biasing means for coupling said forward gripping unit to the front of said cradle and urging said cradle toward said forward gripping unit, and iv) a rear gripping unit secured to the rear of said motor and configured to grip the inner surface of said enclosure when the output shaft of said motor is extended and to release the inner surface of said enclosure when the output shaft is retracted. - View Dependent Claims (10, 11, 12, 13)
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Specification