Skin freezing systems for treating acne and skin conditions

Abstract

A method and system in accordance with a particular embodiments of the technology includes applying a substance onto skin of a human subject. An applicator is then applied to the subject to cool a region of the subject. After cooling the tissue, a nucleation initiator is used to initiate a freeze event in the tissue. The nucleation initiator can be an ice crystal that inoculates the skin upon contact to create a predictable freeze event therein. The time of contact between the ice crystal and the skin can be controlled to achieve desired effects.

1 . A method for predictably freezing a subject's skin at a desired predictable time, comprising:
 lowering a temperature of the skin below a freezing point of fluid in the skin so that the skin is at a first temperature;   causing an ice crystal to contact the skin to inoculate the skin and to create a predictable freeze event therein; and   controlling a time of contact between the ice crystal and the skin so that the predictable freeze occurs at a desired time.   
     
     
         2 . The method of  claim 1 , further comprising physically contacting a surface of the skin with the ice crystal. 
     
     
         3 . The method of  claim 1 , further comprising introducing the ice crystal into the subject using a catheter so that the ice crystal contacts a dermal layer of the skin. 
     
     
         4 . The method of  claim 1 , further comprising forming the ice crystal in a cryoprotectant solution located on the skin. 
     
     
         5 . The method of  claim 4 , further comprising
 maintaining the temperature of the skin at the first temperature for a first treatment period, wherein the first temperature is more than 7 degrees C. below the freezing point of the fluid in the skin; and   after the first treatment period, cooling the cryoprotectant solution from a temperature above a freezing point of the cryoprotectant solution to a temperature below the freezing point of the cryoprotectant solution to form the ice crystal therein.   
     
     
         6 . The method of  claim 4 , further comprising diluting a cryoprotectant concentration on a skin surface so as to raise a freezing point of the diluted concentration to a value above a temperature of the cryoprotectant solution so that formation of the ice crystal does not require that the skin temperature be lowered below the first temperature. 
     
     
         7 . The method of  claim 1 , further comprising using ultrasound energy to create the ice crystal either in the skin or in a substance in contact with the skin. 
     
     
         8 . The method of  claim 1 , wherein the first temperature is at least 10 degrees C. below the freezing point of the fluid in the skin prior to inoculating the skin. 
     
     
         9 . The method of  claim 8 , further comprising:
 maintaining the first temperature for a first treatment period;   after the first treatment period has expired, lowering the skin temperature to a second temperature lower than the first temperature to create the ice crystal; and   maintaining the second temperature for a second treatment period.   
     
     
         10 . The method of  claim 9 , further comprising after the second treatment period has expired, rapidly warming a surface of the skin to a third temperature higher than the first or second temperature. 
     
     
         11 . The method of  claim 10 , further comprising:
 maintaining the third temperature for a third treatment period, wherein the third temperature is a cold therapeutic temperature within 5 degrees C. of the freezing point which causes minimal damage to epidermal tissue; and   allowing the surface of the skin to warm to room temperature or above room temperature.   
     
     
         12 . The method of  claim 1 , wherein the first temperature is less than 3 degrees C. below the freezing point of the fluid prior to inoculating the skin. 
     
     
         13 . The method of  claim 1 , further comprising maintaining the first temperature for a predetermined period of time to create a predetermined level of skin supercooling prior to causing the ice crystal to contact the skin. 
     
     
         14 . The method of  claim 1 , further comprising
 detecting the freeze event; and   controlling a length of time of the freeze event by controlling when the temperature of the skin is raised to a temperature above the freezing point of the fluid in the skin based on detection of the freeze event.   
     
     
         15 . The method of  claim 1 , further comprising forming the ice crystal prior to lowering the temperature of the skin below the freezing temperature of the fluid. 
     
     
         16 . The method of  claim 15 , further comprising forming the ice crystal after lowering the temperature of the skin below the freezing temperature of the fluid. 
     
     
         17 . The method of  claim 1 , further comprising using a coupling media in contact with the skin to aid in removing heat from the skin, and wherein the coupling media includes an ice nucleating agent, a hydrogel, and/or a freezing point depressant. 
     
     
         18 . The method of  claim 1 , further comprising:
 applying a coupling media to the skin, the coupling media having a medium therein capable of forming ice crystals; and   establishing a temperature of an applicator in thermal contact with the coupling media to predictably freeze a portion of the medium in physical contact with a skin surface such that the frozen portion of the medium causes freezing of the skin.   
     
     
         19 . The method of  claim 18 , wherein the coupling media comprises a crosslinked polymer which includes water, and wherein the coupling media has a specific ratio of water-monomer-crosslinker content so as to have a predetermined freezing point higher than either −40, −25, −20, or −15 degrees C. 
     
     
         20 . The method of  claim 19 , wherein the crosslinked polymer is a hydrogel. 
     
     
         21 .- 40 . (canceled)