Abstract:
A self-contained, handheld probe for measuring at least one parameter of skin condition, has one or more light sources that may be used to project light upon the skin. The light projected is of a selected wavelength known to generate a specific fluorescence that is indicative of the skin parameter of interest in accordance with a known correlation. To produce the proper excitation light, a light source generating that wavelength is used or a broader spectrum of light is selectively filtered to pass the wavelength of interest. Lenses, fiber optic elements or waveguides may be employed to project the light onto the skin at a specific location and/or to deliver the skin response to a light detector, which measures the light signal from the skin. and generates an output signal indicative of the value of the at least one parameter. The probe may be used to measure skin age, photodamage and/or proliferation.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to apparatus and methods for testing the skin, and more particularly, for evaluating characteristics of skin based upon the skin&#39;s fluorescence characteristics when illuminated with light of a selected range of wavelengths.  
       BACKGROUND OF THE INVENTION  
       [0002]     The monitoring and maintenance of healthy skin is an important concern for most people. Typically, people examine their skin using a mirror in a setting with natural, incandescent and/or fluorescent lighting. This self examination process is used by a person to ascertain the condition of their skin and potentially to treat the skin with various therapies and preparations in order to improve the condition of the skin. For example, upon viewing the skin in the mirror and ascertaining that the skin looks oily, the selection and use of a washing and/or drying agent may be employed. The presence of wrinkled skin may indicate that a moisturizer or other wrinkle treatment would be advisable. Beside visual inspection, consumers have little concrete scientific information regarding the status of their skin&#39;s health, particularly elements relating to the skin aging processes and the extent of invisible photodamage beneath the skin surface. The first signs of skin “aging” noticed by consumers are fine lines and wrinkles around the eyes, yellowing of the skin, and development of pigmented spots. At this point, the majority of the skin damage has been done, and the process of repair is difficult if not impossible. In addition to the skin conditions that are readily visible in normal lighting environments, there are conditions and indicators of skin health and age that are invisible to inspection using a mirror in typical lighting. For example, subsurface conditions of the skin, such as UV photo damage to subsurface layers (mainly due to exposure to the sun), etc., will not necessarily be apparent by simply viewing the surface of the skin in a mirror. It is now known that inspection of the skin utilizing various wavelengths of light and/or polarized light can illuminate and reveal skin conditions which would otherwise be imperceptible. In addition, these alternative illuminating techniques can highlight and emphasize visible conditions, such as wrinkles or acne. Known techniques for sub-surface or enhanced surface viewing typically involve photography, wherein a flash unit which is capable of producing light of a particular wavelength is activated and an image captured with a camera. Various filters may also be employed in this process. Ultraviolet (UV) photography utilizing a flash unit filtered to produce ultraviolet A light and a camera that is filtered so that only visible light enters the lens produces images that are visually enhanced with regard to pigmentation, the presence of the bacteria p. acnes and horn. A variation of ultraviolet photography has been termed the “sun camera” where ultraviolet A light is used to illuminate the skin and an ultraviolet A sensitive digital camera is used to record the ultraviolet light reflected from the skin. In this arrangement, both pigment distribution and the surface features of the skin are visually enhanced. While the foregoing photographic techniques have proven valuable and useful for analyzing the condition of the skin, they require fairly sophisticated and expensive equipment and the use of photographic techniques and are difficult to quantitate. In addition to photographic techniques, spectrometric apparatus and techniques are also known for evaluating skin condition. One such technique measures fluorescence of the skin in response to light in the 295 nm excitation wavelength range as an indicator of skin age. Prior spectrometric analysis techniques required expensive laboratory instruments and a trained technician to collect and analyze the data gathered. There is a need therefore for an inexpensive and uncomplicated apparatus and method for evaluation and quantitation of the skin&#39;s overall health as measured by it&#39;s proliferative status, overall physiological “age” and the extent of photodamage of particular skin areas, that would be suitable for consumer use.  
       SUMMARY OF THE INVENTION  
       [0003]     The problems and disadvantages associated with conventional apparatus and techniques utilized to view or assess the skin&#39;s condition are overcome by the present invention, which includes a probe for measuring at least one parameter of skin condition, including an illuminator for generating optical radiation to be projected upon the skin to be examined. A detector measures the optical signal from the skin in response to the excitation energy projected on the skin by the illuminator and generates an output signal indicative of the value of the at least one parameter. The probe is a self-contained unit that may be held in a human hand. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  is a side view of a device in accordance with an embodiment of the present invention for measuring the skin condition;  
         [0005]      FIG. 2  is a diagrammatic view of interior components of the invention of  FIG. 1 , e.g., as revealed by taking the cross-section of  FIG. 1 ;  
         [0006]      FIG. 3  is an end view of the invention of  FIG. 1 ;  
         [0007]      FIG. 4  is an alternative embodiment of the invention shown in  FIG. 3 ;  
         [0008]      FIG. 5  is a diagrammatic view of an embodiment of the present invention;  
         [0009]      FIG. 6  is a block diagram of an embodiment of the present invention;  
         [0010]      FIG. 7  is a schematic diagram of an embodiment of the present invention;  
         [0011]      FIGS. 8 and 9  are graphs showing a correlation between age and skin fluorescence emission at 500 nm wavelength when exited by light of 400 nm; and  
         [0012]      FIG. 10  is a graph of skin health related to age. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]      FIG. 1  shows a probe  10  having an elongated housing  12 , dimensioned for retention in a single hand of a user. The probe  10  has a plurality of controls  14 , e.g., in the form of buttons which may be depressed to allow the user to select a particular test to be conducted and to initiate testing. An LCD (liquid crystal display)  16  is provided on the probe  10  to display instructions and test results to the user. In taking test measurements with the probe  10 , a ready light  18  indicates when the testing can be initiated, e.g., certain tests may require that the probe  10  be seated against the skin at the skin contact end  22  to exclude environmental light from passing between the skin contact end  22  and the skin. When referring to radiation, the term “light” as used herein describes optical radiation in the wavelength regions from the ultraviolet region through the infra-red regions and is not confined to the wavelengths that are only detected by the human eye. A zero reading of light sensed would indicate proper seating of the probe, thus triggering illumination of the ready light  18 . A USB port  20  is provided on the probe  10  to allow data that is collected by the probe  10  to be downloaded to a computer or a storage device.  
         [0014]      FIG. 2  diagrammatically shows the interior components of the probe  10 , which include one or more lights or other optical radiation sources  24  for generating light  26  for illuminating the skin S. The output  26  from the light  24  is passed through an illumination filter  28  which may be used to select a particular range or set of wavelengths. The filtered light  30  passes through the filter  28  and impinges on an illumination lens  32  which redirects and/or focuses light  34  upon the skin S at a selected location. Light  36  may be reflected from the skin surface S or may penetrate the skin causing the skin to emit or fluoresce light  38 . The reflected and/or emitted light  36 ,  38  is directed towards the detection lens  40  which focuses and redirects the light signal  42  to a detector filter  44 . The detector filter  44  may be utilized to filter out undesired wavelengths of light and pass the selected wavelengths of interest  46 . The filtered light  46  from the skin S impinges upon detector  48  which senses the intensity of the light  46  of the selected wavelengths. This intensity measurement is provided to a microprocessor  52  which may include suitable circuitry for converting an analog signal to digital data. The operation of the light or lights  24  is controlled by light controller  50  under the direction of the microprocessor  52 . The microprocessor  52  would include a memory for storing the signal data generated by the detector  48 . A transceiver  54  acting through antenna  56  may be utilized to communicate the data received from the detector  48  to a remote computer. Alternatively, the transceiver  54  and antenna  56  may be utilized to download instructions from a computer. A battery  58  is provided for powering the above described components of the probe  10 .  
         [0015]      FIG. 3  shows the skin contact end  22  of the probe  10 . A separator  35  terminates prior to contact with the skin S thereby allowing reflected light  36  (see  FIG. 2 ) to be received by the detector lens  40 . In the alternative, the separator  35  could extend to the skin surface to be coextensive with the contact end  22 , thereby occluding reflected light  36  and allowing only light  38  emitted from below the surface of the skin S to enter the detector lens. In contrast, second and third separator walls  60  and  62  are coterminal with the skin contact end  22  thereby preventing surface reflections from a second illumination aperture  64  from entering the second detector aperture  66 . A separator  35  need not be used if the detector filter  44  filters out all but the desired reflected/emitted wavelength(s) and the detection lens  40  is shielded from those desired wavelength(s) present in ambient lighting.  
         [0016]      FIG. 4  illustrates another embodiment of the probe  68  wherein a plurality of separators  70 , some or all of which allow reflection from the skin&#39;s surface into an adjacent detector aperture  72  or alternatively may be coterminal with the probe skin contact end thereby blocking reflected light.  
         [0017]      FIG. 5  diagrammatically illustrates the process conducted by the present invention  110  and shows additional alternatives pertaining to illumination and detection. More particularly, to measure the skin proliferation rate, light of 295 nm is utilized as the excitation light  86  impinging upon the skin S. The desired wavelength range of the emitted light from the skin monitored by detector  102  is 340 nm. Light reflected  90  or fluoresced/emitted  92  from the skin is passed through the lens  96  and through detector filter  100 , which eliminates all wavelengths except for those in the 340nm range. The monitored emission  101  is detected by the detector  102 , generating a signal to the microprocessor  52 . In measuring the skin proliferation rate utilizing 295 nm excitation light and measuring the emission of 340 nm light from the skin, the light source  74  may be a flash lamp with a 295 nm narrow pass filter  78  (plus or minus 10 to 20 nm) or a fluorescent bulb coated with a specific phosphor that emits within this range with little or no emission at 340 nm. The output of the fluorescent lamp can also be filtered with a narrow band pass filter  78  to make the source more monochromatic (295 nm plus or minus 10 to 15 nm). The light source  74  could also be a mercury lamp without a phosphor coating on the bulb envelope which is filtered through a narrow band pass filter  78  to isolate the 296.7 nm wavelength excitation. As an alternative to the light source  74  and filter  78  combination, a xenon—chloride laser source  104  could be used to excite the skin, in which case the laser  104  would generate illuminating/excitation light of 308 nm. It should be observed that if a laser is utilized, the lens  84  is not necessarily required unless the physical layout of the probe  110  requires the laser beam to be spread or to redirected to the desired focal point on the surface of the skin. The detector  102  for measuring skin proliferation rate (295 nm excitation/340 nm emission) may be a silicon-based semiconductor photocell filtered with a narrow band pass filter  100  (to limit the radiation reaching the photo cell to wavelengths between 335 to 350 nm with high blockage of radiation below 335 nm). Alternatively, a long pass Schott filter such as a WG335 filter of 3 mm thickness could also be used to block the short wavelengths. As a further alternative, ordinary window glass of about 2 mm thickness could be used as the filter  100  to block the short UVB emission wavelengths.  
         [0018]      FIG. 5  shows that a fiber optic  82  could be utilized to transmit light  80 ,  86  to the skin on the illumination/excitation side of the probe  110 . Similarly, a fiber optic  94  could be utilized for receiving the reflected light  90  and/or emitted light  92  from the skin on the detector side of the probe  110 . In either instance, the lenses  84 ,  96  may or may not be utilized depending upon the physical layout of the probe  110 , e.g., depending upon whether the fiber optic elements  84 ,  94  are adequate to position the excitation light  86  on the proper focal point of the skin, and the receiving fiber optic  94  is positioned correctly to absorb the admitted radiation  90 ,  92  for detection. Still referring to  FIG. 5 , when the probe  110  is utilized to determine chronological skin age, light in the range of 400 nm is used for excitation/illumination and light of 500 nm is monitored on the detector  102  side of the probe  110 . In that particular application, the light source  74  may be an LED  106  with emitting wavelengths between approximately 380 nm and 420 nm. Alternatively, the light source  74  may be a flash lamp, such as a xenon arc lamp filtered with a narrow band pass filter  78 , which allows passage of wavelengths between 380 nm to 420 nm. Alternatively, the light source  74  may be a fluorescent light with emissions in the 380 to 420 nm wavelength region, with or without a narrow band pass filter  78 . As yet a further alternative, a mercury vapor lamp could be utilized as the light source  74  which emits wavelengths in the 400 to 410 nm range that are filtered with along band pass filter  78  such as a UV400 cut-off filter to limit exposure to UV radiation. As yet a further alternative, the light source  74  may be a tungsten-halogen light source that admits a continuous spectrum of wavelengths that are filtered with a narrow band pass filter  78  permitting the passage of light in the 380 to 420 nm region. When measuring chronologic skin age, the monitoring photo detector  102  may be a silicon photocell with a filter  100  to block out wavelengths below 470 nm. Any other type of semiconductor photocell that produces a signal based on the photoelectric effect of light to measure light intensity may be used. A long pass filter blocking wavelengths below 470 nm could also be utilized with such a photocell.  
         [0019]      FIG. 6  shows a block diagram of an embodiment of the probe system  120  including a power control system  122  which would distribute power to the circuit components of the probe  120  from the power system  123 , for example a battery or batteries, in a conventional manner. The power control system provides suitable voltages to the various components of the system, i.e., the illumination system  124 , the light control system  126 , the detection system  128 , etc. Preferably, the power control system  122  includes a timer that causes automatic shutdown to conserve battery power if there is a lack of activity over a predefined time period. The power system  123  may be a replaceable battery and/or a recharging system for recharging rechargeable batteries via an external charger which could be plugged into the probe  120 . As described above, the illumination system  124  may include one or a plurality of different light sources, which may emanate a full spectrum of light or may provide light in a narrower wavelength range, e.g., an LED. The illumination system  124  preferably has a predetermined maximum capacity for illumination. The light control system  126 , as described above, may include lenses, fiber optics or waveguides to direct, transform and funnel the light emanating from the illumination system  124  to and from the skin. As noted above, filters within the light control system  124  may be utilized to block specific wavelengths and to pass particular wavelengths of light on the way to the surface of the skin (excitation) and/or returning from the surface of the skin for detection. Preferably, the housing is provided with a means to prevent undesired ambient light from interfering with the detection system  128  for certain tests. As noted above, the detection system includes a photodetector for sensing light intensity. Data concerning the intensity of light received by the detection system  128  is conveyed to the main control system  130 , which may include a digital processor. The probe  120  may be analog or may include a digital processor. The main system control  130  responds to operator input to initiate readings and otherwise controls the other components of the probe  120  to coordinate their activities. The main system control  130  presents the results obtained by operating the probe  120  to the operator via an LCD screen, or by remote communication through a transceiver to a computer. This is shown as the operator interface system  132  which may be in the form of an LCD, a transceiver, and/or a communications link e.g., USB to an external computer. A USB connector may be utilized to charge the batteries  58  of the device  10 , as well as to exchange data. The operator interface system  132  may display the value of the skin fluorescence to the operator and may also display system status, errors and operator directions.  
         [0020]      FIG. 7  shows an embodiment of the probe system  140  utilizing an illumination source/exciter  142 , which generates light  144  for impinging upon the surface of the skin and for penetrating the surface to cause sub-surface fluorescence. The illumination light  144  produced by the exciter  142  may be 295 nm plus or minus 10 nm. In the UV-B band, maximum exposure to the skin should not exceed 10 mJ/cm 2  to prevent erythogemic responses from the skin. As before, a signal detector  152  measures the amount of light  150  emanating from the skin and is blind to the illumination light  144  and ambient light. The amount of light detected by the detector  152  may be displayed to the operator/user as a value from 0 to 1,000 for example. The probe system  140  may include a reflector  146  and a reference target  148 . The reflector  146  redirects the illuminating light  144  onto a signal detector  148 —the reference target, which may be the same signal detector  152  for the purpose of establishing a reference value from the illuminating light  144 . In operation, the operator powers the probe system  140 , whereupon the probe system checks itself and auto-calibrates itself. The operator then places the unit over the skin to be tested and presses a “read” button. The illumination light  142  illuminates the skin via the optical system, be that via wave guides, optical fibers or lenses, as is required. The reference value of the illumination light  144  is read at the reference target  148  by virtue of the operation of the reflector  146  which directs the illumination light  144  at the reference target  148 . The light is then redirected back to the skin causing fluorescence, e.g., producing a 340 nm responsive emission from the skin. The signal detector  152  reads the fluorescence level as light signal  150  and converts the ratio of the fluorescence level over the reference level to a displayed value of 0 to 1,000 indicating the proliferation level. For example, a ratio of zero may have an output of zero and ratio of 1 to 1 may correspond to an output of 1,000. The operator may then read the fluorescence level from the LCD display of the probe system  140 . Upon release of the “read” button, the illumination light  142  is powered off and the operator interface system  132  will maintain the reading until the unit powers down or is shut off. Subsequent pressing of the “read” button may overwrite previous readings.  
         [0021]      FIGS. 8 and 9  are graphs showing the correlation between skin fluorescence at 500 nm to skin photodamage/age. The determination of the extent of photodamage is conducted by measuring the 400 nm excitation/500 nm fluorescence emission on two skin sites, i.e., one that is routinely exposed to sun—such as the forearm or the face (dorsal), and then obtaining a second measurement at a site that is typically non-exposed—such as the upper inner arm, or on a non-exposed buttock or upper thigh area (volar). The difference in fluorescence between dorsal and volar surfaces has been shown to correlate with photodamaged skin age and chronological age.  
         [0022]      FIG. 10  is a graph showing the correlation between the ratio of fluorescence behavior over two emission bands and age (skin health). As indicated in U.S. patent application Ser. No. 10/735,188, entitled Method of Assessing the Skin by Kollias and Stamatas, filed Dec. 12, 2003 (attorney docket no. J&amp;J 5092), which is incorporated by reference herein, the fluorescence ratio of the 295 nm excitation: 340 nm emission/390 excitation: 480 emission signals is a measure of skin health that is highly correlated with age. These measures can be conducted on photodamaged or non-photodamaged skin and yield results that are highly correlated with skin age. These measurements are conducted with the same instrumentation and techniques described above, with electronic circuitry doing the computations to determine the ratio and correlate the results versus age, as presented by Kollias and Stamatas in the referenced application. Accordingly, the probe  10  of the present invention can be utilized to measure skin age and the degree of photodamage.  
         [0023]     It is understood that while the invention has been described in conjunction with the detailed description thereof, that the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the claims.