Needle probe, apparatus for sensing compositional information, medical drain, method of measuring a thermal property, and method of sensing compositional information
The invention relates to sensing compositional information about material by measuring thermal properties of the material. In one arrangement there is provided a needle probe for sensing compositional information. The probe comprises a needle having a tip region. A resistive element is attached to the needle at the tip region. A measurement system is configured to: 1) drive an electrical current through the resistive element to apply heating to the resistive element, and 2) measure an electrical response of the resistive element to the heating. A processing unit analyses the measured electrical response of the resistive element to the heating to determine compositional information about material in contact with the tip region.
1 . A method of detecting a medically abnormal portion of human or animal skin, comprising:
bringing a resistive element of a probe element into contact with a target portion of the human or animal skin;
driving an electrical current through the resistive element to apply heating to the resistive element while the resistive element is in contact with the target portion;
measuring an electrical response of the resistive element to the heating; and
determining, using a processing unit, a heat transfer characteristic of the target portion based on a variation in a temperature of the resistive element against time represented by the electrical response, wherein the heat transfer characteristic represents how efficiently heat is conducted away from the resistive element; and
determining, using the processing unit, that the target portion is medically abnormal based on the determined heat transfer characteristic.
2 . The method of claim 1 , wherein the heat transfer characteristic of the target portion is determined at a plurality of different times and the using the determined heat transfer characteristic to detect whether the target portion is medically abnormal comprises detecting a change in a composition of the target portion over time that is indicative of the target portion being medically abnormal.
3 . The method of claim 1 , wherein the target portion comprises a mole or other irregularity on the human or animal skin.
4 . The method of claim 1 , further comprising:
bringing the resistive element into contact with one other portion of the human or animal skin different from the target portion; driving the electrical current through the resistive element to apply heating to the resistive element while the resistive element is in contact with the one other portion of the human or animal skin different from the target portion; measuring an electrical response of the resistive element to the heating; and determining, using the processing unit, the heat transfer characteristic of the one other portion of the human or animal skin different from the target portion based on the variation in the temperature of the resistive element against time represented by the electrical response,
wherein determining whether the target portion is medically abnormal comprises detecting a difference in the heat transfer characteristic in the target portion, in comparison to the heat transfer characteristic of the one other portion of the human or animal skin different from the target portion.
5 . The method of claim 4 , wherein the target portion is a first mole on the human or animal skin and the one other portion of the human or animal skin is a second mole on the human or animal skin, or the target portion is a first irregularity on the human or animal skin and the one other portion of the human or animal skin is a second irregularity on the human or animal skin.
6 . The method of claim 1 , wherein the heat transfer characteristic comprises the thermal product, √{square root over (ρcκ)}, where ρ is the density, c is the specific heat capacity, and κ is the thermal conductivity.