This application relates to the field of temperature measurement of a living body, and may be implemented before, during or after treatment of the living body for cosmetic or other treatments.
Sensory neurons are nerve cells that transmit sensory information (sight, sound, feeling, etc.). They are activated by sensory input, and send projections (using action potential) to other elements of the nervous system, ultimately conveying sensory information to the brain or spinal cord.
Action potentials are generated by special types of voltage-gated ion channels embedded in a cell's plasma membrane. As can be seen in
One can quantify a neuron's response in terms of its firing rate, the number of action potentials that occur per unit of time. For example, as can be seen in
The equilibrium voltage across the neuron axon membrane for the kth ion is, by convention, the intracellular minus the extracellular potential (Vk=Φi−Φo). It is described by Nernst equation derived by Walther Hermann Nernst in 1888:
Since there are more than one ion involved, the transmembrane voltage Vm can be calculated using the Goldman-Hodgkin-Katz equation:
The feedback-loop of voltage-gated ion channels mentioned above made it difficult to determine their exact behavior. In 1952 Alan Lloyd Hodgkin and Andrew Huxley explained the shape of the action potential by analyzing the electrical circuit of a single axonal compartment of a neuron, consisting of the following components: 1) membrane capacitance, 2) Na channel, 3) K channel, 4) leakage current:
In an aspect, a method for dynamically measuring temperature variations in skin tissue includes providing one or more electrical signal pickup elements on the skin tissue; providing at least one thresholding device to generate one or more agitating signals; providing at least one agitating device on the skin tissue at least some distance from the one or more electrical pickup signal elements; the method comprising: stimulating the skin tissue by applying one or more agitating signals to the agitating element until a neural response is indicated on a display, the neurons responding with a specific frequency modulation; identifying the relevant neural signal by locking on the modulation period; and, processing the neural signal to generate the temperature of the skin at the point of the thresholding device.
In another aspect, the method further includes the steps of: providing treatment to the skin at the point of the thresholding device, in which the treatment is of a type that causes a change in the skin tissue temperature; monitoring any variations in the neural signal frequency during the treatment; and, processing variations to determine any change in temperature of the skin tissue. The method may also include displaying changes in the skin tissue temperature.
In yet another aspect, the one or more agitating signals may be one or more of: an electrical voltage, an electric current; a mechanically driven device, a chemical device or a temperature generating device. The step of providing treatment may be a treatment head that generates EM energy to the skin tissue and the treatment head and the thresholding device may be combined in a single unit.
In yet a further aspect, a programmed controller may be provided and an indication of the temperature may cause the programmed controller to modify the operation of the treatment head.
As the models of the action potential suggest, temperature change will modify the cross membrane potentials and alter the ions transfer rates across the membrane. As can be seen in
One aspect of the present invention is to monitor the temperature of a target tissue. Temperature changes of a target tissue result in changes in action potential firing rates evoked by thermo-receptors within the tissue as can be seen in
1. A thresholding element 302 that provides a stimulus load that generates a low level stimulating signal to evoke action potential.
2. A sensing element (such as an electrode 304 and/or electrode 312) to sense the resulting neural signal.
3. A signal processing element 310 (HW and/or SW based and including a display, a memory and a programmed controller) to analyze the obtained neural signal and deduce the temperature in the stimulus environment.
4. A treatment device 306 which is utilized to treat an area 306 on the body.
The thresholding element 302 can use various stimulation type such as electric voltage, electric current, electric field, mechanical, temperature (hot or cold), chemical and any other stimulation that the neurons might be sensitive to. The stimulating mechanism may be a dedicated stimulus mechanism which is configured for this purpose only, or a combined mechanism which may provide nerve stimulation and/or treatment simultaneously or separately. Thresholding measurements, using one or more thresholding elements, may be done on a target tissue resting at a base temperature state. A base temperature state for the purpose of thresholding may be the natural temperature of the target tissue at room temperature or at any higher or lower induced temperature or set of different temperatures. Thresholding measurements of the target tissue may provide a finger-print profile for the nerve response of the target tissue at a given temperature or at selected different temperatures. During this thresholding or calibration process, the characteristic of the action potential pulses will be stored and processed within the signal processing unit 310. The slope, width and shape of the action potential as well as the correlating frequencies of the action potential firing rates at different stimuli levels and/or temperatures will be analyzed to correlate any changes in at least one of these parameters with the target tissue's temperature.
Once a neuron is stimulated, or a group of neurons, it/they will fire a series of action potentials. The firing will last as long as the stimulus is present. The firing rate depends on the stimulus level. A sensing element 304 for acquiring the nerve signal may be placed at different locations (304. 312) on the body which are proximal to the stimulus location. One example for such a location is seen in
It is also possible to introduce several stimuli that can have different modulation levels to monitor temperature variations in different parts of the body or different depth levels (such as epidermis and dermis). A modulated stimuli, according to one embodiment of the present invention, may be a thresholding stimuli. However, according to another embodiment of the invention, it can be a modulation of a treatment energy.
Once a neuron is stimulated and it fires action potential at a given rate, any variation temperature to the stimulation zone will result in a change of the firing rate. By monitoring this firing rate and analyzing its variations, one can deduce the local temperature change.
In addition to temperature, this method can be used to monitor other types of stimuli that alter the firing rate. It can be used for example to monitor local drugs and other chemicals concentration, mechanical effects, healing progress or other changes in hemostatic state of an organ.
Specifically, temperature induced treatments such as hair removal can be monitored under the present invention. For example, the temperature of the epidermis and the dermis may be monitored during laser treatment. With this information, optimized treatment parameters may be generated to increase treatment efficacy while maintaining treatment safety.
The sensing element or elements 304 and/or 312 (by way of example only) may be placed to optimize neuron signal pickup. In the event treatment on a limb is to be performed, placing an electrode at the end of the limb may be considered and implemented. Another location to place the electrode may be on the upper back or neck, above the spinal cord since all the signals from the sensory neural system go through those locations.
Once the neural signal is measured, the signal processing element 310 may be used to extract the variations in repetition rate and analyze the signal to deduce the temperature in the monitored area and to display the results on a display on unit 310.
In a first step 402, an operator or physician may place sensing/signal pickup electrodes (such as shown in
In a next step 404, a treatment head, such as shown in
In a next step 406, the stimulus/thresholding device 302 is activated and may induce a periodic signal into the tissue.
In a next step 408, the stimulus/agitation level may be increased until the operator observes a neural response that indicates reaching a threshold level. This may be observed on a screen on device 310 or an aural or visual signal provided.
As a result of the reaching of the threshold level, the neurons will respond with a corresponding frequency modulation (410).
In a next step 412, the relevant neural signal may be identified by locking onto the modulation period.
In a next step 414, treatment may be applied with the treatment head or device 306 onto the treatment region 308. With an increase in the body temperature during the treatment process, the frequency modulation will be seen to be modified or changes. This change may be provided to the operator in any form, including a visual or aural indication provided on the display unto in unit 310.
In a next step 416, the variations of the neural signal frequency modulation from the threshold level as the temperature changes may be extracted and processed by the unit 310 to calculate and display temperature information that may be presented on the display in unit 310.
This application is related to and claims priority to U.S. provisional Application Ser. No. 62/110,552, filed Feb. 1, 2015, the entire contents of which are herein incorporated by reference.
Number | Date | Country | |
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62110552 | Feb 2015 | US |