# US 8,784,403 B2 · Wax micro actuator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,784,403 B2 - Document ID: US8784403B2 - Status: Granted - Kind: B2 - Application number: 12/447,225 - Filed: 2007-10-25 - Published: 2010-06-10 - Granted: 2014-07-22 - Earliest claimed: 2006-10-26 - Assignees: Cellnovo Limited - Applicants: Joseph John Cefai; Julian Llewellyn Shapley - Inventors: Joseph John Cefai; Julian Llewellyn Shapley - Web page: https://patentgrep.com/patent/US8784403B2 ## CPC - F04B 43/043: {Micropumps} - F04B 35/00: Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for - F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F) ## Abstract An actuator comprises a cavity containing a working medium that reversibly expands as it undergoes a phase change from a solid to a liquid state, a diaphragm disposed adjacent the cavity such that expansion and contraction of the expandable working medium causes the diaphragm to deflect, and a semiconductor element disposed in the cavity, wherein the semiconductor element is adapted to heat the working medium to cause it to undergo the phase change into the liquid state. The actuator may be used in a pump for an infusion system. ## Claims ### Claim 1 An actuator comprising: a cavity containing a working medium that reversibly expands as it undergoes a phase change from a solid to a liquid state; a diaphragm disposed adjacent the cavity such that expansion and contraction of the expandable working medium causes the diaphragm to deflect; and a semiconductor element disposed in the cavity, wherein the semiconductor element is immersed in the working medium adjacent to the diaphragm and is adapted to heat the working medium to cause it to undergo the phase change into the liquid state. ### Claim 2 (depends on 1) An actuator according to claim 1, wherein the cavity comprises side walls and the semiconductor element is positioned substantially equidistant from each of the side walls of the cavity. ### Claim 3 (depends on 1) An actuator according to claim 1, wherein the semiconductor element is positioned within the cavity to permit substantially free flow of liquid working medium around the semiconductor element. ### Claim 4 (depends on 1) An actuator according to claim 1, wherein the cavity contains substantially no gas. ### Claim 5 (depends on 1) An actuator according to claim 1, wherein only some of the working medium in the cavity is intended to undergo the phase change during actuation. ### Claim 6 (depends on 1) An actuator according to claim 1, wherein the semiconductor element is a semiconductor diode. ### Claim 7 (depends on 1) An actuator according to claim 1, wherein the diaphragm is substantially planar when the working medium is in its solid state. ### Claim 8 (depends on 1) An actuator according to claim 1, wherein the diaphragm is biased and/or is resilient such that it returns to a position as before melting of the working medium. ### Claim 9 (depends on 1) An actuator according to claim 1, further comprising a gearing system to amplify either a linear or volume displacement of the diaphragm. ### Claim 10 (depends on 9) An actuator according to claim 9, wherein the gearing system includes a gearing piston adapted to deflect a gearing diaphragm, larger than the actuator diaphragm. ### Claim 11 (depends on 1) An actuator according to claim 1, wherein electrical connections to the semiconductor element are disposed at least partially within the cavity. ### Claim 12 (depends on 11) An actuator according to claim 11, wherein the electrical connections are positioned adjacent the diaphragm. ### Claim 13 (depends on 12) An actuator according to claim 12, wherein the working medium fills a space between the diaphragm and the electrical connections. ### Claim 14 (depends on 1) An actuator according to claim 1, wherein the working medium includes wax. ### Claim 15 (depends on 14) An actuator according to claim 14, wherein the wax is substantially pure. ### Claim 16 (depends on 14) An actuator according to claim 14, wherein the wax includes a blend of different two waxes, one having a higher molecular weight than the other. ### Claim 17 (depends on 16) An actuator according to claim 16, wherein the working medium comprises approximately 60% hexatriacontane and approximately 40% paraffin wax. ### Claim 18 (depends on 1) An actuator according to claim 1, wherein the cavity is bounded by an actuator body and the diaphragm. ### Claim 19 (depends on 18) An actuator according to claim 18, wherein the body is unitary. ### Claim 20 (depends on 18) An actuator according to claim 18, wherein the body has a removable end remote from the diaphragm to permit filling and/or draining of the cavity with the working medium. ### Claim 21 (depends on 18) An actuator according to claim 18, wherein the diaphragm is connected to a frame member attached to the body. ### Claim 22 (depends on 18) An actuator according to claim 18, wherein the diaphragm is attached directly to the body. ### Claim 23 A pump for pumping liquid therapeutic product, comprising: an actuator, the actuator including: a cavity containing a working medium that reversibly expands as it undergoes a phase change from a solid to a liquid state; a diaphragm disposed adjacent the cavity such that expansion and contraction of the expandable working medium causes the diaphragm to deflect; a semiconductor element disposed in the cavity, wherein the semiconductor element is immersed in the working medium adjacent to the diaphragm and is adapted to heat the working medium to cause it to undergo the phase change into the liquid state; and a pumping chamber having an inlet and an outlet, wherein a volume of the pumping chamber is caused to change by actuation of the actuator. ### Claim 24 (depends on 23) A pump according to claim 23, wherein the pumping chamber volume is less than approximately 100 μl. ### Claim 25 (depends on 23) A pump according to claim 23, further comprising an inlet valve. ### Claim 26 (depends on 25) A pump according to claim 25, further comprising an outlet valve. ### Claim 27 (depends on 26) A pump according to claim 26, wherein the outlet valve has a higher activation pressure than the inlet valve. ### Claim 28 An infusion system comprising: a pump, the pump including a pumping chamber having an inlet and an outlet, wherein a volume of the pumping chamber is caused to change by actuation of the actuator; and an actuator, the actuator including: a cavity containing a working medium that reversibly expands as it undergoes a phase change from a solid to a liquid state; a diaphragm disposed adjacent the cavity such that expansion and contraction of the expandable working medium causes the diaphragm to deflect; a semiconductor element disposed in the cavity, wherein the semiconductor element is immersed in the working medium adjacent to the diaphragm and is adapted to heat the working medium to cause it to undergo the phase change into the liquid state.