as shown in fig2 , the inventive device 21 comprises an assembly of components , which are shown in the exploded view in fig1 . the device 21 comprises an assembly of the upper enclosing layer 1 , the upper substantially rigid member 2 , the microporous highly compressible foam member 3 , the highly compressible area containing the electromechanical switch circuit 4 , the highly incompressible area containing the electronic analysis components 5 , the lower substantially rigid member 6 , the flexible substrate 7 , and the lower enclosing layer 8 . in operation , the device 21 would be placed within the shoe under the sock liner , or insole , toward the heel and in contact with the upper side of the energy absorbing foam in the heel of the shoe , as shown in fig3 . the user would then engage in an activity , such as walking or running , which causes a force to be applied to the system , thereby causing partial failure of the energy absorbing foam . although a single cycle of the force for the activity may not cause total failure to the energy absorbing foam , repeated compression cycles will accumulate enough partial failures to result in total failure to the energy absorbing foam . additionally , the environment within the shoe may typically contain sweat and excess heat generated from the user during use . the environment may be naturally augmented by addition of water from rain or standing puddles that may enter the show during its use . the device 21 may be constructed of materials that inherently resist degradation throughout the life of the device , or separate the device from environment throughout its life . a method of using the device includes its insertion within the shoe , participating in an activity that compresses the device , physically interfacing with the device to determine its cumulative use , and the determination that the device has reached its end of useful life . the upper enclosing layer 1 , as shown in fig4 , may contain an adhesive layer 61 for attachment to the microporous highly compressible foam member 3 ( see fig1 ), a semitransparent continuous layer 62 to receive the artwork member 63 , and a transparent continuous impermeable layer 64 . the adhesive layer may be chosen from a variety of adhesives common to the fabrication of microporous foam devices . the preferred embodiment uses a pressure sensitive adhesive ( psa ), such as 3m 300lse , which increases its adhesive function throughout the compressive use of the device . the semitransparent continuous layer 62 functions to protect the inside of the device from exposure to the environment of the shoe and also serve to receive the artwork member 63 . the materials of construction of the semitransparent continuous layer may be chosen from any material that is opaque under typical lighting to the user and will transmit light from the indicators . the preferred embodiment is constructed using a durable vinyl graphic film , such as 3m controltac plus graphic film , but other materials can be employed . the artwork member 63 may consist of the logos , instructions for use , and references to the wear reference values and is intended to convey information regarding the device 21 to the user . the materials of construction of the artwork member 63 may be chosen from any color - fast printing material and may be adhered to the semitransparent continuous layer through a variety of means including inkjet , silkscreen , or laser printing which are common to someone skilled in the art of printing . a preferred embodiment may be constructed with solvent based inks such that no deleterious effects occur to the artwork during the use of the device 21 . for example , the high heat and moisture will not detrimentally affect a solvent based ink , thereby retaining the legibility of the artwork till the end of life of the invention . the transparent continuous impermeable layer 64 further protects the device from the environment found with the shoe . the materials of construction may be chosen from any lamination material typical to the lamination method , such as a film and adhesive material . the lower enclosing layer 8 , as shown in fig7 , contains a lower adhesive layer 121 for attachment to the shoe , a continuous impermeable layer 122 , and an upper adhesive layer 123 for attachment to the flexible substrate 7 ( see fig1 ). the lower and upper adhesive layers 121 , 123 may be chosen from a variety of adhesives common to the fabrication of microporous foam devices . a preferred embodiment uses pressure sensitive adhesive ( psa ), such as 3m 300lse , which increases its adhesive function throughout the compressive use of the device . the continuous impermeable layer 122 functions to protect the inside of the device from exposure to the environment of the shoe and assist the elements of the device to return to their original position after the compression cycle . the materials of construction may be chosen from any material with a high yield strength such that the flexing that occurs during the compression cycle is resisted and the layer is forced to return to its original position after the compression cycle . the materials of construction must also be chosen such that it resists moisture ingress . although the layer may be constructed of materials such as spring steel or polyimide film , one preferred embodiment uses polyester . the highly compressible area 5 , shown in cross section in fig8 , functions to receive the compressive force from the heel of the user during the compression cycle , convert the compressive force to an electrical pulse and return the area to its original position after the compression cycle . the area contains the upper substantially rigid member 2 , the microporous highly compressible foam member 3 , the electromechanical switch 4 , and the lower substantially rigid member 6 . the upper substantially rigid member 2 functions to distribute the compressive force exerted by the heel of the user during the compression cycle to the electromechanical switch 4 and to the microporous highly compressible foam material 3 . the material of construction of the upper and lower substantially rigid members 2 , 6 are chosen such that , during a compression cycle , the material will resist deformation and not retain a permanent deformation and return to its original shape after the compression cycle . although it can be constructed of any material that will not permanently deformed during the compression cycle , a material with a high yield strength is preferred , such as spring tempered stainless steel . the microporous highly compressible foam member 3 is chosen such that it compresses during the compression cycle and returns to its original shape after the compression cycle without retaining any permanent deformation or loss of height . although any microporous material can be used , such as neoprene or silicone foam , a preferred embodiment uses a polyurethane high density foam , known as poron . particular to this invention is the choice of the microporous material with characteristics such that it generates a counter force greater than the nondestructive compressive force generated by the user . more particularly , the density and thickness of the microporous foam is chosen to overcome the compression force of the user such that the electromechanical switch 4 is not fully compressed . also particular to this invention is the choice in the lateral width of the microporous foam member that is chosen to be significantly larger than the thickness of the foam member such that the compression cycle causes movement of the foam member predominantly perpendicular to the surface of the foam member . although a variety of ratios could be established to achieve this objective , the preferred embodiment has a diameter of about two inches and a thickness about ⅛ of an inch . the electromechanical switch 4 is compressed during the compression cycle closing the electrical path connected to the electronics components in the highly incompressible area 5 , thereby generating a corresponding electrical pulse . although the materials of construction may be chosen from any that compress during the compression cycle and return to their original position after the compression cycle , the preferred embodiment uses a dome type switch which , when compressed , closes the electrical connection from the positive and negative side of the circuit . dome type switches are known in the art and commonly found in electronic assemblies . particular to this invention is the selection of a dome switch with an internal counter compression force , commonly referred to as activation force , that is great enough to resist the nondestructive compression force generated by the user during a compression cycle . also particular to this invention is the location of electromechanical switch 4 relative to the end of one side of the invention as shown in fig9 . the location of the switch 4 is chosen to improve the accuracy of the invention such that the electromechanical switch 4 will be compressed , regardless of the angle between the ground and the shoe of the user shown in fig1 or the distribution of the compression force based on the arch type , as shown in fig1 . a user with a high angle 143 ( see fig1 ) will transition from the heel to the toe during the activity , thereby compressing the electromechanical switch 4 . however , if the location of the switch 4 were chosen to close to the heel a user with a low angle 142 or negative angle 141 may not overcome the internal counter compression force if the electromechanical switch 4 were located further back toward the heel . also , if the arch of the user tends to be high 152 ( see fig1 ), the placement of the switch 4 toward the front of the arch will insure it is fully compressed during its use . the electromechanical switch 4 is centered between 1 . 5 and 2 . 0 inches from one end of the lower enclosing layer 8 . the use of this device 21 may include activities that include fully destructive compressions and less destructive compressions , such as from walking . this can be better understood by fig5 , which shows the relative force of the heel strike for a variety of users as compared to their static standing weight . thus , a distinction between a more destructive force and minimally destructive force can be created . chockalingam , et . al . described in “ a pilot study of the reaction forces at the heel during walking with the application of four different wound dressing ” that the average force of a walking heel strike is 1 . 3 times the force of the user of the shoe . therefore , it can be shown that a heel strike of , say 250 pounds , may produce a fully destructive compression of a shoe . whereas , a 175 pound user , walking may produce a partially destructive compression . it is important to this device to be able to distinguish a partially destructive compression from a fully destructive compression . a single electrical pulse generated during the compression cycle by the electromechanical switch 4 corresponds to a single compression cycle . particular to this invention is the pulse analysis method , which includes the comparison of the time characteristics of the pulse to predetermined reference values , and correspondingly augmenting the cumulative destructive value based on the result of this comparison . critical to the accuracy of the cumulative destructive value is the determination of whether the compression cycle is non destructive , partially destructive , or fully destructive . a nondestructive compression cycle will not cause any actuation by the electromechanical switch 4 , and therefore will not augment the cumulative destructive value . the determination of whether the compression cycle is partially or fully destructive is accomplished by the analysis of the time characteristics of the electrical pulse and by comparing the result of that analysis to predetermined reference values . the electrical pulse is described by the electrical voltage changing from one state to another as shown in fig1 . although the electrical pulse can be arranged to change from a low voltage to a high voltage during the compression cycle , in one embodiment , the waveform changes from a high voltage 162 to a low voltage 161 . the electrical pulse has a time characteristic which may be described by the length of time the electrical pulse remains in the low state 163 . specifically , the device distinguishes the types of compression cycles based on the length of time the electrical pulse is in the low state . the type of compression cycle is determined by comparing the length of time the pulse remains in the low state to a reference time period . the reference time period for the partially destructive cycle and fully destructive cycle are dependent on the internal counterforce of the highly compressible area 3 and may be determined empirically based on the specific design of the device 21 . in one embodiment , it has been found that the reference time period for the fully destructive compression cycle is generally half the time of the partially destructive cycle . for example , the pulse will remain in the lower state for a longer time when the user is in a walking cycle because one foot of the user remains on the ground at all times . this distinction is used to augment the cumulative destructive value stored in the microcontroller . the cumulative destructive value is used to summarize the total use of the device 21 within the shoe and is correlated to the total wear of the shoe by the user . the value is stored in the memory of the microcontroller and is augmented by the logic of the internal software shown in fig1 . the electronics of the device 21 include a microcontroller , or any suitable processing unit . that processing unit is in electrical communication with a storage device , such as a memory . the memory may be static or dynamic . furthermore , it may be volatile or non - volatile . in some embodiments , a non - volatile memory is used to store the instructions executed by the processing unit . the non - volatile memory , such as eeprom or flash rom , may be a separate component , or may be embedded in the processing unit . the electronics may include ram to hold dynamic data , such as counters and other variables . further , the electronics may include indicating means that allow the results from the device 21 to be viewed by the user . returning to fig1 , the cumulative destructive value is set to zero at the beginning of the use of the device 21 and is augmented in value throughout the use of the device . the pulse analysis method also includes the augmentation of the cumulative destructive value by an amount corresponding to a partially destructive or fully destructive compression . specifically , the cumulative wear counter will be augmented by a smaller amount , such as of a unit , for a partially destructive compression cycle and a full unit for a fully destructive compression cycle . the cumulative destructive value is used by the comparative indication method to indicate the cumulative wear of the device . the augmentation determines the cumulative destruction of the shoe . this value is then used to create an indication to the user . the comparative indication method includes comparing the cumulative destructive value to predetermined shoe wear references and indicating the cumulative destructive value to the user , such as by an integrated visual display . the predetermined shoe wear references may be established by the manufacturers of the shoes . for example , typically , a running shoe manufacturer will recommend the shoe be replaced at about 400 miles , or about 250 , 000 compression cycles . although the shoe wear reference may be chosen to be exactly the same as the recommended value , a lower or higher value may be chosen to accommodate the type of shoe in which the invention is used . in one embodiment , the indication may comprise a visual display assembly that may include a plurality of illuminating elements that are electrically connected to the microcontroller . the comparative indication method includes comparing the cumulative destructive value to various percentages of the show wear reference number and providing an indication to the user . for example , in one embodiment , if the cumulative destructive value is greater than about of the shoe wear reference number , a first indicator may be illuminated . if the cumulative destructive value is greater than a second percentage of the show wear reference number , such as about ⅓ of the shoe wear reference number , a second indicator may be illuminated . if the cumulative destructive value is greater than a third percentage , such as about ⅞ of the shoe wear reference , a third indicator may be illuminated . if the cumulative destructive value is about equal to the shoe wear reference number , a fourth indicator may be illuminated . other percentages may be used , and different numbers of indicators may also be employed . the indicators are located within the highly incompressible area 5 and are electrically illuminated by the microprocessor . although the indicators can be comprised of any type of electrical light , a preferred embodiment may use surface mount leds . the choice of the four indicators is chosen such that a user would be given sufficient warning to the user that the shoe should be replaced before they enter into a training routine or race . additionally , more indicators can be used to indicate other functions . for example , the indicators can be chosen to occupy the same general space but be composed of different colorations or the indicator can be a single led which changes colors through the variation of applied voltage . additionally , an indicator can be used to demonstrate that the device is working correctly or another indicator can be used to demonstrate that the invention is augmenting the cumulative destructive value correctly . once illuminated , the visual display may remain illuminated for a fixed period of time , or may be controlled by a user operation , such as actuation of a button or switch . the highly incompressible area 5 shown in fig6 contains a substantially inflexible circuit board 42 , an electronic microcontroller 43 to receive the electronic pulse from the electromechanical switch 4 , a power supply 44 , a highly incompressible impermeable coating ( not shown for clarity ) and a visual display assembly 45 . the highly incompressible area functions to receive the electrical pulse from the electromechanical switch 4 and analyze its characteristics and display an indication of the cumulative destructive value visually to the user . the substantially inflexible circuit is constructed of materials common to the methods of pcb construction and is chosen of a thickness that is substantially inflexible during the compression cycle . the power supply is an electrical power supply chosen appropriately to power the microprocessor and the visual display assembly . in one preferred embodiment , the power supply is a lithium coin battery , however a plurality of power supplies may be used . for example , two or more power sources may be used to separately energize the visual display assembly and the electronic microcontroller . the electronic microcontroller executes the incorporated software of fig1 to receive the input of the electrical pulse from the electromechanical switch 4 , analyze its characteristics , accumulate a wear value , and energize the visual display assembly . although any electronic microcontroller can be chosen , in one embodiment , an atmel atiny microcontroller is used . the highly incompressible impermeable coating functions to isolate the electronic components from the environment of the shoe and mechanically stabilize the electronic components from the flexing forces of the compression cycle . although any coating typical for the encapsulation of electronics can be chosen , a preferred coating may be loctite e - 05cl epoxy . it should be noted that in accordance with one embodiment , this device is manufactured using a cast - in - place assembly method . although cast - in - place , or molding methods , are known in the art for electronics encapsulation , the choice of a sufficiently dense microporous foam material and a conformal coating with a rapid curing rate and sufficiently high viscosity such that the conformal coating may be injected into the open area above the electronic components thereby filling the open areas and the conformal coating curing before it penetrates into the microporous foam thereby degrading the performance of the microporous foam is specific to one embodiment . the flexible electrical substrate 7 ( see fig1 ) functions to stabilize the device , retain the elements in their arrangement , and retain the electrical interconnections between the electrical components of the highly compressible area 4 and the electrical components of the highly incompressible area 5 . the material of construction is chosen with a sufficient tensile yield strength to return to the original shape after the compression cycle such as fiberglass resin , polyimide , or polyester pcbs or a lamination of spring tempered steel alloy and an insulative layer . the electrical interconnections are constructed of materials typical for pcb fabrication , such as copper traces . the present disclosure is not to be limited in scope by the specific embodiments described herein . indeed , other various embodiments of and modifications to the present disclosure , in addition to those described herein , will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings . thus , such other embodiments and modifications are intended to fall within the scope of the present disclosure . further , although the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose , those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes . accordingly , the claims set forth below should be construed in view of the full breadth and spirit of the present disclosure as described herein .
a device , inserted in a running shoe is used to track the accumulation of destructive compression cycles within the shoe and to indicate this information to the user through a series of integrated indicators . the device has an advantage of being able to be placed in any shoe without compromising the construction or performance of the shoe . an additional advantage of the invention is the improved accuracy of the information by improving both the stability and longevity of the sensor system and the ability to distinguish destructive , partially destructive and nondestructive compressions . another advantage of the invention is the reduction of the cost of construction while achieving a lifetime in excess of the shoe . yet another advantage of the invention is the user interface , which is contained completely within the device allowing the user to view the information within the shoe .