WO1993016667A1

WO1993016667A1 - Cryogenic probe

Info

Publication number: WO1993016667A1
Application number: PCT/US1993/001782
Authority: WO
Inventors: R. Rox Anderson; Fredric L. Milder
Original assignee: Implemed, Inc.
Priority date: 1992-02-26
Filing date: 1993-02-25
Publication date: 1993-09-02
Also published as: AU3735593A

Abstract

A cryogenic probe (10') including a cold reservoir (18) having a phase change material and a removable tip in thermal communication with the cold reservoir (18). The cryogenic probe (10') is useable with a thermal charging stand, having at least a heat sink (46), which is capable of precooling the cold reservoir (18) prior to use. Heat is pumped between the cryogenic probe (10') and the thermal charging stand (22) by thermoelectric heat pumps (30, 44).

Description

CRYOGENIC PROBE

RELATED APPLICATION This application is a Divisional application of Serial No. 07/842,885, filed February 26, 1992, entitled CRYOGENIC PROBE (Our File No. MSPI-001XX) .

FIELD OF THE INVENTION The invention relates to the field of medical instruments and more particularly to the field of cryogenic medical instruments.

BACKGROUND OF THE INVENTION

One method of treating of papilloma and other body surface lesions involves placing a cryogenic probe on the portion of the body surface to be treated and allowing the surface layer of cells to freeze. The act of freezing the papilloma or lesion results in the death of the surface layer of cells, similar to that which occurs in blistering. When the surface layer thaws, the dead cells are sloughed away leaving a new surface layer.

Typically, in a clinician's office, such treatment is performed using a cotton swab which is first dipped in liquid nitrogen. The swab is then applied to the body surface to be treated. The liquid nitrogen cools the swab, which in turn cools the body surface. Once the temperature of the swab is raised above the freezing point of water, the swab is removed from the body surface.

Because liquid nitrogen is difficult to store and because replenishing the supply of liquid nitrogen requires expensive and specialized equipment, several attempts have been made to create a cryogenic probe which does not require liquid nitrogen as its heat sink. One attempt is disclosed in the patent of Eidus, U.S. Patent 3,133,539. This device uses a semiconductor thermoelectric heat pump to pump heat from a probe tip into a heat sink. The heat sink consists of a reservoir of water or other suitable liquid. This device is electrically attached to an external electrical source and required a large reservoir because of the heat sink material used.

SUMMARY OF THE INVENTION The present invention relates to a portable cryogenic probe having an internal power source and a reservoir of a phase change material which may be precooled and is capable of absorbing a large amount of heat from the tip of the probe.

In one embodiment, the cryogenic probe includes a thermoelectric heat pump and portable power source and actively pumps heat from a probe tip to the reservoir by means of a thermoelectric heat pump. This embodiment may be used in conjunction with a charging stand which, in one embodiment, includes a power supply for electrically charging the portable power source of the cryogenic probe and a thermoelectric heat pump for thermally charging the reservoir of the cryogenic probe.

Another embodiment of the cryogenic probe includes a second thermoelectric heat pump in which, in conjunction with the first thermoelectric heat pump aids in pumping heat from the probe tip to the reservoir. The embodiment of the charging stand used with this embodiment includes a power supply to electrically charge the portable power source of the cryogenic probe and a heat sink to aid in dissipating heat absorbed by the reservoir during use.

Yet another embodiment of the cryogenic probe includes a reservoir without a thermoelectric heat pump. This embodiment may be used in conjunction with an embodiment of a charging stand that includes two adjacent thermoelectric heat pumps and which is used to precool the reservoir prior to use. This embodiment of the cryogenic probe may also be used in conjunction with an embodiment of a charging stand that includes two thermoelectric heat pumps in conjunction with a second reservoir of phase change material located in the charging stand. Heat is pumped from the reservoir of the charging stand by both thermoelectric heat pumps, while the cryogenic probe is being used, so as to precool the reservoir of the charging stand. Heat is pumped from the reservoir of the cryogenic probe to the reservoir of the charging stand when the cryogenic probe is position in the charging stand.

BRIEF DESCRIPTION OF THE DRAWINGS These and further features of the invention may be better understood with reference to the accompanying specification and drawings in which:

Fig. 1 is a block diagram of an embodiment of the invention; Fig. la is a perspective view of an embodiment of an active cryogenic probe of the invention;

Fig. lb is a perspective view of an embodiment of a passive cryogenic probe of the invention;

Fig. 2 is a block diagram of an embodiment of the invention including the active cryogenic probe shown in Fig. la and a charging stand;

, Fig. 3 is a diagram of an embodiment of one end of the cold reservoir of the invention;

Fig. 3a is a diagram of another embodiment of one end of the cold reservoir of the invention;

Fig. 4 is a block diagram of another embodiment of the invention including the cryogenic probe shown in Fig. la and a charging stand;

Fig. 4a is a block diagram of an embodiment of the invention including the passive cryogenic probe shown in Fig. lb and a charging stand; and

Fig. 4b is a schematic diagram of another embodiment of the invention including the passive cryogenic probe shown in Fig. lb and a charging stand. DESCRIPTION OF THE PREFERRED EMBODIMENTS Structure:

Referring to Fig. 1, a cryogenic probe 10 of the invention includes a probe tip 16 and a cold reservoir 18. The probe tip 16 transfers heat from a body 8, in contact with the probe tip 16, to the cold reservoir 18, thereby cooling the body 8. The cryogenic probe 10 may be constructed as an active cryogenic probe or a passive cryogenic probe. An active cryogenic probe actively pumps heat from the probe tip 16 to the cold reservoir 18. In a passive cryogenic probe, heat is transferred from the probe tip 16 to the cold reservoir 18 simply by conduction.

Considering each type of cryogenic probe briefly, and referring to Fig. la, an embodiment of an active cryogenic probe 10' constructed in accordance with the invention includes a housing 12 having a switch 14, an external electrical connector 20 and a removable, disposable or sterilizable, probe tip 16. The cryogenic probe 10' is of a size and shape which permits it to be held comfortably in the hand of an operator, such as a clinician.

The switch 14 controls the active pumping of heat relative to the probe tip 16. The position and orientation of the switch 14 on the housing 12 permits the operator to control the direction of the active pumping of heat using a finger or thumb of the hand holding the active cryogenic probe 10'. The external electrical connector 20 permits the power source of the active cryogenic probe 10' to be charged when the probe is not being used.

Fig. lb is a perspective diagram'of an embodiment of a passive cryogenic probe 10" constructed in accordance with the invention. As in the embodiment of the active cryogenic probe 10' shown in Fig. la, this embodiment includes a housing 12 and a removable, disposable or sterilizable, probe tip 16. However, since this embodiment does not actively pump heat from the probe tip 16, it does not include a switch 14 or external electrical connector 20. Because this passive cryogenic probe 10" does not include the components of the active cryogenic probe 10' required to actively pump heat from the probe tip 16, the passive cryogenic probe 10" may be made smaller than the active cryogenic probe 10'. In the embodiments shown, the probe tip 16 is made of a material which has good thermal conductance, such as aluminum. The probe tip 16 is removably attachable to either the active or passive cryogenic probe 10', 10" by any number of attachment means known to the art. These include, but are not limited to screw threads or snap-lock connectors. The use of a removable probe tip 16 permits the probe tip 16 to be changed between patients to lessen the danger of contamination. The removable probe tip 16 also permits for more rapid recharging of the cold reservoir 18 as will be discussed below.

In more detail, Fig. 2 depicts a block diagram of an embodiment of the active cryogenic probe 10' shown in Fig. la, with the probe tip 16 removed and the active cryogenic probe 10' positioned in a charging stand 20. In this embodiment, a semiconductor thermoelectric heat pump 30 is located adjacent the end of the housing 12 to which is attached the probe tip 16. When the probe tip 16 is in position on the active cryogenic probe 16, the base 17 of the probe tip 16 is in thermal contact with one surface of the semiconductor thermoelectric heat pump 30. The opposite surface of the semiconductor thermoelectric heat pump 30 is in thermal contact with the cold reservoir 18. The semiconductor thermoelectric heat pump 30 is capable of pumping heat from the probe tip 16 into the cold reservoir 18 when current flows through the semiconductor thermoelectric heat pump 30 in one predetermined direction and is capable of pumping heat from the cold reservoir 18 into the probe tip 16 when the flow of current through the semiconductor thermoelectric heat pump 30 is reversed. The material of the cold reservoir 18 changes phase as heat is pumped into or out of it. As heat is pumped from the cold reservoir 18, the material of the cold reservoir 18 changes phase and "stores cold". In this phase, the material of the cold reservoir 18 is capable of acting as a heat sink for the semiconductor thermoelectric heat pump 18. Some of the phase change materials which are suitable for the application shown include water and ethylene glycol, water and alcohol and water and glycerine. These materials undergo a solid/liquid phase transition in the range of temperatures desired. That is, a cold reservoir 18 containing 5 to 15 grams of any of these materials is capable of reaching temperatures of 0°C to less than -35°C.

Referring also to Fig. 3, since phase materials typically undergo a change in volume as a cooling phase transition occurs, the cold reservoir 18, in one embodiment, is constructed with a bellows 32 at the end of the cold reservoir 18 opposite the end to which the probe tip 16 is attached. As the phase material expands (arrow E) , the bellows 32 expand to accommodate the increased volume. Alternatively other embodiments of the cold reservoir 18, for example as shown in Fig. 3a, incorporating flexible and resilient end materials 34 may be used to permit the end of the cold reservoir 18 to expand, without rupturing, when cooled.

The semiconductor thermoelectric heat pump 30 is powered by a power source 40, such as a high energy density battery, located within the housing 12. This power source is capable of producing relatively high current (for example 1.5 amps) at a low voltage (for example 2 volts) . Probe electronics 42, which will be discussed in detail below, are also located within the housing 12.

The switch 14 connects the power source 40 with the semiconductor thermoelectric heat pump 30. In one position, the on position, the switch 14 permits current to flow from the power source 40 through the semiconductor thermoelectric heat pump 30 in the direction required for the semiconductor thermoelectric heat pump 30 to pump heat from the probe tip 16 into the cold reservoir 18. In a second position,, the reverse position, the switch 14 permits current to flow from the power source 40 through the semiconductor thermoelectric heat pump 30 in the opposite direction, permitting heat to be pumped from the cold reservoir 18 to the probe tip 18. In a third position, the off position, the semiconductor thermoelectric heat pump 30 is disconnected from the power source 40.

In the embodiment shown, the charging stand 22 is capable of charging the active cryogenic probe both electrically and thermally. When the probe tip 16 has been removed, to reduce the amount of material between the cold reservoir 18 and the charging stand 22, and the active cryogenic probe 10' has been placed in the charging stand 22, one surface of the semiconductor thermoelectric pump 30 is in thermal contact with a surface 24 of the charging stand 22. Additionally, the external electrical connector 20 of the active cryogenic probe 10' engages an electrical contact 23 in the charging stand 22. Power from an AC source is converted by base electronics 26 to DC current which passes through the electrical contact 23 of the charging stand 22, enters the external electrical contact 20 of the active cryogenic probe 10' and charges the power source 40. The base electronics 26 determines the level of charge of the power source 40 and maintains the power source 40 in a charged state.

Additionally, the base electronics 26 detects the presence of the active cryogenic probe 10' in the charging stand 22, either by virtue of the current being drawn to charge the power source 40 or by virtue of a microswitch (not shown) located in the charging stand 22 and closed by the physical presence of the active cryogenic probe 10'. Once the base electronics 26 detects the presence of the active cryogenic probe 10' in the charging stand 22, the base electronics 26 acts also to thermally charge the cold reservoir 18. Specifically, the base electronics 26 energizes a second semiconductor thermoelectric heat pump 44 located within the charging stand 22 to pump heat from the surface 24 of the charging stand 22 to a heat sink 46. Because the surface 24 is in thermal contact with the semiconductor thermoelectric heat pump 30 of active cryogenic probe 10' heat is drawn from the semiconductor thermoelectric heat pump 30. The base electronics 26 also energizes a fan 48 to help dissipate the heat absorbed by the heat sink 46.

This arrangement of components provides a cold surface 24 which is capable of absorbing heat from the cold reservoir 18 of the active cryogenic probe 10' by way of the semiconductor thermoelectric heat pump 30 as follows. The probe electronics 42 of the active cryogenic probe 10' detects when the active cryogenic probe 10' is positioned in the charging stand 22 and acts to thermally charge the cold reservoir 18. The probe electronics 42 does this by passing current through the semiconductor thermoelectric heat pump 30, such that the semiconductor thermoelectric heat pump 30 pumps heat from the cold reservoir 18 to the surface 24 of the charging stand 22. Effectively, heat is pumped from the cold reservoir 18 by the semiconductor thermoelectric heat pump 30 to the surface 24 of the charging stand and out through the heat sink 46 by means of a second semiconductor thermoelectric heat pump 44. The probe electronics 42 uses a temperature probe 50 located in the cold reservoir 18 to determine when the cold reservoir 18 is at the desired temperature.. When this predetermined temperature is reached, the probe electronics 42 disconnects power to the semiconductor thermoelectric heat pump 30. Power supplied to the semiconductor thermoelectric heat pump 30 either may be drawn from the power source 40, which is being recharged by the base electronics 26 or power may be drawn directly from the base electronics 26 by way of the current path including electrical contact 23, the external electrical contact 20 and the probe electronics 42. Fig. 4 depicts another embodiment of an active cryogenic probe 10'. In this embodiment, to compensate for the fact that the charging stand 22' does not include a semiconductor thermoelectric heat pump 44 to help cool the surface 24 and thereby draw heat from the cold reservoir 18, a second semiconductor thermoelectric heat pump 30' has been added. This second semiconductor thermoelectric heat pump 30' is connected such that when the active cryogenic probe 10' is in the charging stand 22', both semiconductor thermoelectric heat pumps 30, 30' are energized. The semiconductor thermoelectric heat pumps 30, 30' are arranged such that heat pumped from the cold reservoir 18, by the first semiconductor thermoelectric heat pump 30 is then pumped from the first semiconductor thermoelectric heat pump 30 by the second semiconductor thermoelectric heat pump 30'. The heat is then pumped into the surface 24 of the charging stand 22' and out through the heat sink 46. The base electronics 26 of the charging stand 22' again detects the presence of the active cryogenic probe 10' and activates a fan 48 to help cool the heat sink 46. This arrangement is capable of rapidly cooling a cold reservoir 18 containing 30 grams of phase change material from a starting temperature of +35° c. In this embodiment, the cold reservoir 18 is not precooled prior to use. The semiconductor thermoelectric heat pumps are used to pump heat from the cold reservoir 18 after use to reduce the temperature of the cold reservoir 18 to about ambient prior to its next use.

Fig. 4a depicts an embodiment of the passive cryogenic probe 10'' shown in Fig. lb. In this embodiment no electrical components are located in the housing 12 of the passive cryogenic probe 10". A microswitch 60 detects the presence of the passive cryogenic probe 10" in the charging stand 22a and signals the base electronics 26 to reduce the temperature of the cold reservoir 18, by energizing two semiconductor thermoelectric heat pumps 44', 44". The semiconductor thermoelectric heat pumps 44', 44" are arranged such that heat pumped from the surface 24 by the first semiconductor thermoelectric heat pump 44" is then pumped from the first semiconductor thermoelectric heat pump 44" by the second semiconductor thermoelectric heat pump 44'. The heat is then pumped into the heat sink 46 which is cooled by a fan 48 controlled by the base electronics 26 of the charging stand 22a. As heat is pumped from the surface 24, heat diffuses to the surface 24 of the charging stand 22a from the cold reservoir 18, thereby reducing the temperature of the cold reservoir. The embodiment shown is capable of reducing a cold reservoir 18 containing 1 to 5 grams of phase change material to -35°C.

Fig. 4b depicts yet another embodiment of a charging stand 22a' which may be used in conjunction with the passive cryogenic probe 10". As with the previous embodiment, the charging stand 22a' includes two semiconductor thermoelectric heat pumps 44', 44". However, the charging stand 22a' also includes a second cold reservoir 70. The two semiconductor thermoelectric heat pumps 44', -44" are disposed on either side of the second cold reservoir 70 with one semiconductor thermoelectric heat pump 44" in contact with surface 24 and the- second semiconductor thermoelectric heat pump 44 ' in contact with the heat sink 46. When the passive cryogenic probe 10" is not present in the charging stand 22a' current is passed through each semiconductor thermoelectric heat pump 44', 44" in such a direction that heat is pumped from the second cold reservoir 72 through the surface 24 by one semiconductor thermoelectric heat pump 44" and through the heat sink 46 by the second semiconductor thermoelectric heat pump 44'. However, when the passive cryogenic probe 10" is present in the charging stand 22a' current is passed through each semiconductor thermoelectric heat pump 44', 44" in such a way that heat is pumped from the surface 24 into the second cold reservoir 70 by one semiconductor thermoelectric heat pump 44" and from - li ¬ the second cold reservoir 70 out through the heat sink 46 by the second semiconductor thermoelectric heat pump 44'. This arrangement provides a precooled second cold reservoir 70 which is capable of rapidly cooling the cold reservoir 18 of the passive cryogenic probe 10". The arrangement has the added benefit that when the passive cryogenic probe 10" is not in contact with the charging stand 22a' , the surface 24 of the charging stand 22a' is warmed by the heat pumped out of the second cold reservoir 70 thereby preventing frost from forming on the surface 24. This arrangement is capable of cooling the cold reservoir 18 to -35°C. Operation:

To use the active cryogenic probe 10', the active cryogenic probe 10' is removed from its charging stand 22 (or 22') and the probe tip 16 attached. The switch 14 is placed in the on position and the probe tip 16 allowed to cool by heat being drawn into the cold reservoir 18. The probe tip 16 is touched to the papilloma to be treated and the skin allowed to freeze. Once the desired degree of freezing has taken place, the switch 14 is placed in the reverse position and the probe tip 16 permitted to heat by heat being pumped from the cold reservoir 18. When the probe tip 16 is warm enough to be removed from the skin, the probe tip 16 is withdrawn from the skin surface, the probe tip 16 removed and the active cryogenic probe 10' place in the charging stand 22 (or 22') for recharging.

To use the passive cryogenic probe 10", the passive cryogenic probe 10" is removed from its charging stand 22a (or 22a') and the probe tip 16 attached. Once the probe tip 16 is on the passive cryogenic probe 10" it is allowed to cool by the conduction of heat to the cold reservoir 18. Once the probe tip 16 is at the desired temperature, the probe tip.16 is touched to the papilloma to be treated and the skin allowed to freeze. Unlike the previous embodiment, once the desired degree of freezing has taken place, the probe tip 16 permitted to heat only by the heat generated by the body in contact with the probe tip 16. It is for this reason that the cold reservoir 18 contains much less material than in the case of the active cryogenic probe 10' . When the probe tip 16 is warm enough to be removed from the skin, the probe tip 16 is withdrawn from the skin surface, the probe tip 16 removed from the passive cryogenic probe, and the passive cryogenic probe 10" replaced in the charging stand 22a (or 22a') to recharge.

It should be noted that the probe electronics 42 may include an indicator, such as a light emitting diode visible on the housing, which may indicate when the cold reservoir is at the desired temperature. Additionally, the cryogenic probe 10 may include infra-red or ultrasonic transducers which are capable of measuring the depth to which tissue freezing is occurring.

These and other examples of the concept of the invention illustrated above are intended by way of example and the actual scope of the invention is to be determined solely from the following claims.

Claims

CLAIMS What is claimed is:

1. A cryogenic probe comprising: a housing having a first end and a second end; 5 a cold reservoir including a phase change material, that undergoes a phase change when said cryogenic probe is used within a predetermined range of operating temperatures, said cold reservoir located within said housing; and a probe tip removably attached to said first end of 10 said housing and in thermal communication with said cold reservoir.

2. The cryogenic probe of claim 1 wherein said phase change material is selected from the group of phase change materials comprising:

1_.5 ethylene glycol and water; alcohol and water; and glycerine and water.

3. The cryogenic probe of claim 1 further comprising: a thermoelectric heat pump located within said housing 20 between said probe tip and said cold reservoir; and a power source located within said housing and in electrical communication with said thermoelectric pump.

4. The cryogenic probe of claim 3 further comprising a multiposition switch in electrical communication with said

25 power source and said thermoelectric heat pump, said switch operative, in a first position, to cause a current to flow from said power source through said thermoelectric heat pump in one direction and thereby to cause heat to flow from said probe tip to said cold

30 reservoir, and said switch operative, in a second position, to cause a current to flow from said power source through said thermoelectric heat pump in an opposite direction and thereby to cause heat to flow from said cold reservoir to said probe tip.

5. The cryogenic probe of claim 3 wherein said thermoelectric heat pump is a semiconductor heat pump.

6. The cryogenic probe of claim 1 wherein said cold reservoir further comprises a bellows.

7. The cryogenic probe of claim 1 wherein said cold reservoir further comprises a distendable resilient end.

8. A cryogenic probe charging stand comprising: a housing having a surface which is capable of being in thermal contact with a cold reservoir of a cryogenic probe supported by said cryogenic probe charging stand; a power source located within said housing for supplying power to said cryogenic probe supported by said cryogenic probe charging stand; a heat sink in thermal contact with said surface.

9. A cryogenic system comprising:

-a cryogenic probe comprising: a housing having a first end and a second end; a cold reservoir comprising a phase change material, said cold reservoir located within said housing; and a probe tip removably attached to one end of said housing and in thermal communication with said reservoir; and a charging stand operative for cooling said cold reservoir.

10. The cryogenic probe of claim 1, wherein said predetermined range of operating temperatures is 0°C to - 35°C.

11. The cryogenic probe of claim 1, wherein said predetermined range of operating temperatures is 25°C to 40°C.

12. The cryogenic probe of claim 3, wherein said predetermined range of operating temperatures is 0°C to -

35°c.

13. The cryogenic probe of claim 3, wherein said predetermined range of operating temperatures is 25°C to 40°C.

14. A method for cooling an object comprising the steps of: pumping heat from a probe tip to a cold reservoir, said cold reservoir comprising a phase change material that absorbs heat by changing phase from a solid phase to a liquid phase; applying said probe tip to said object, whereby said object is cooled; and pumping heat from said cold reservoir to a thermal charging unit to cause said phase change material to change phase from a liquid phase to a solid phase.

15. The method of claim 11, wherein said probe tip is precooled.

16. A method for cooling an object comprising the steps of: pumping heat from a cold reservoir of a cryogenic probe having a cooling tip to a thermal charging unit thereby causing a phase change material in said cold reservoir to change phase from a liquid phase to a solid phase; and applying said cooling tip to said object, thereby cooling said object.

17. A cryogenic system comprising: a cryogenic probe comprising: a cryogenic probe housing having a first end and a second end; and a cold reservoir comprising a phase change material that undergoes a phase change when said cryogenic probe is used within a predetermined range of operating temperatures, said cold reservoir located within said cryogenic probe housing; and a charging stand adapted to receive said cryogenic probe, said charging stand cooling said cold reservoir when said cryogenic probe is received by said charging stand.

18. A cryogenic probe charging stand comprising: a charging stand housing adapted to receive a cryogenic probe comprising a thermal reservoir, said charging stand housing comprising an interface adapted to make thermal contact with said cryogenic probe and to absorb heat from said thermal reservoir of said cryogenic probe when said cryogenic probe is received by said charging stand housing; and a heat sink in thermal contact with said interface, said heat sink adapted to dissipate heat absorbed by said interface.

19. The cryogenic probe charging stand of claim 18, further comprising an electronic unit having a power supply, wherein said electronic unit is in electrical communication with at least one electrically powered component of said cryogenic probe charging stand, and wherein said electronic unit controls electrical power distribution from said power supply to said at least one electrically powered component.

20. The cryogenic probe charging stand of claim 19, further comprising a fan in electrical communication with said electronic unit and located so as to aid in dissipating heat absorbed by said heat sink.

21. The cryogenic probe charging stand of claim 20, further comprising a sensor located within said cryogenic probe charging stand and adapted to detect receipt of said cryogenic probe by said charging stand housing.

22. The cryogenic probe charging stand of claim 21, wherein said fan is in electrical communication with said sensor and wherein said fan is activated to aid in dissipating heat absorbed by said heat sink in response to detection of said cryogenic probe by said sensor.

23. The cryogenic probe charging stand of claim_.19, wherein said power supply recharges a cryogenic probe battery within said cryogenic probe.

24. The cryogenic probe charging stand of claim 19, wherein said heat sink comprises: a heat sink reservoir containing a phase change material that absorbs heat by changing phase; and a thermoelectric heat pump in thermal contact with said heat sink reservoir, said thermoelectric heat pump adapted to pump heat from said heat sink reservoir.

25. The cryogenic probe charging stand of claim 24, wherein said phase change material undergoes a phase change from a solid phase to a liquid phase.

26. The cryogenic probe charging stand of claim 18, wherein said housing is adapted to support said cryogenic probe.

27. A cryogenic probe charging stand comprising: a charging stand housing capable of receiving a cryogenic probe, said housing comprising a surface adapted to make thermal contact with a cryogenic probe cold reservoir, wherein said charging stand housing is adapted to support said cryogenic probe; a first thermoelectric heat pump having a first side and a second side, wherein said first side is in thermal contact with said surface, and wherein said first thermoelectric heat pump pumps heat away from said first side to said second side to cool said surface;

^"a charging stand cold reservoir having a third side and a fourth side, wherein said third side is in thermal contact with said second side of said first thermoelectric heat pump, and wherein said charging stand cold reservoir includes a phase change material that undergoes a phase change and absorbs heat -by changing phase to draw heat from said third side to cool said second side; a second thermoelectric heat pump having a fifth side and a sixth side, wherein said fifth side is in thermal contact with said fourth side of said charging stand cold reservoir, and wherein said second thermoelectric heat pump pumps heat away from said fifth side toward said sixth side to cool said fourth side; and a heat sink in thermal contact with said sixth side of said second thermoelectric heat pump, for dissipating heat from said sixth side.

28. The cryogenic probe charging stand of claim 27, wherein said first thermoelectric pump pumps heat from said second side to said first side to warm said surface and to cool said charging stand cold reservoir when said cryogenic probe is not in said cryogenic probe charging stand.

29. A method for cooling an object with a cryogenic system, said cryogenic system including a cryogenic probe adapted to make thermal contact with a detachable cooling tip, said cryogenic probe including a first cold reservoir having a phase change material that absorbs heat by changing phase; and a charging stand adapted to receive said cryogenic probe, said charging stand including at least one thermoelectric pump, a second cold reservoir, and a heat sink, said method comprising the steps of: removing said cooling tip from said cryogenic probe; placing said cryogenic probe into said charging stand; actively pumping heat from said first cold reservoir toward said second cold reservoir with said at least one thermoelectric pump to cause said phase change material of said first cold reservoir to change phase; removing said cryogenic probe from said charging stand; attaching said cooling tip to said cryogenic probe; drawing heat from said cooling tip toward said first cold reservoir; and applying said cooling tip to said object.

30. A method for cooling an object with a cryogenic system, said cryogenic system including a cryogenic probe adapted to make thermal contact with a detachable cooling tip, said cryogenic probe including a cold reservoir having a phase change material that absorbs heat by changing phase and at least one thermoelectric heat pump; and a charging stand adapted to receive said cryogenic probe, said charging stand having a heat sink, said method comprising the steps of: removing said cooling tip from said cryogenic probe; placing said cryogenic probe into said charging stand; actively pumping heat from said cold reservoir toward said heat sink with said at least one thermoelectric pump to cause said phase change material of said cold reservoir to change phase; removing said cryogenic probe from said charging stand; attaching said cooling tip to said cryogenic probe; pumping heat from said cooling tip toward said cold reservoir with said at least one thermoelectric pump; and applying said cooling tip to said object.