our invention generally provides plastic piezoelectric sensing member 10 , protected by flexible encapsulation member 11 which carries spaced supports 12 at its end parts , and associated electrical circuitry 13 for signal amplification and annunciation . sensing member 10 is formed by two elongate flexible polymeric piezoelectric elements 14 , 15 both of similar shape but with one element 14 slightly smaller than the second element 15 . these piezoelectric elements are arrayed in symmetric stacked fashion . by reason of their different size and array , the peripheral edges of the two elements will not be coincident . these elements are normally formed from a larger piece of polymeric material by some type of shearing or cutting action . this action often leaves roughness about the peripheral edges of the elements , causes deformation of a permanent or semi - permanent nature in the peripheral area or both . these irregularities often create electrical noise when the elements are used or may even cause shorting of a temporary or permanent nature between conductive portions of adjacent sensing elements . the difference in size of the elements in our invention tends to prevent or substantially alleviate these problems . the two sensing elements are arranged in a stacked array as shown especially in the illustration of fig4 . the elements are so positioned as to have their negative surfaces adjacent each other and are physically interconnected with electrically non - conductive adhesive 16 forming a continuous membranous - like coating therebetween . the negative surfaces of the two sensing elements must be in fairly immediate adjacency for this array of elements to be operative so the layer of insulating adhesive 16 must be relatively thin , generally in the order of three to five thousandths of an inch , but yet that layer must be continuous to prevent any direct electrical contact between the conductive surfaces of the two sensing elements . the particular shape and size of the sensing elements is not critical to our invention , but preferably it will be in the range of 0 . 5 inches in width and 3 . 0 inches in length for normal use on a human body . the particular material from which the sensing elements are formed is one of the polyvinylidene fluoride compounds such as that known as &# 34 ; kynar &# 34 ;, as manufactured and merchandised by pennwalt chemicals . undoubtedly other similar piezoelectric polymers that generate a voltage upon flexion would be operative with our switch , if possibly not so effectively . these films provide a thin , tough polymeric sheet with conductive surface coatings that emit a voltage of a few tenths of a volt upon activation . such polymeric piezoelectric elements are interconnected into electrical circuitry with some difficulty and generally specialized connecting devices are required , especially such as shown in fig4 . here conductive metallic foil patches 17 , in the instant device formed of copper , are interconnected to each of the outer positive surfaces of the two stacked sensing elements . these metallic foil patches , of the rectilinear shape illustrated and with a width somewhat less than the width of the smaller sensing element , provide a contacting surface of some area . the strips are adhered to the conductive surface of the sensing elements by electrically conductive adhesive 18 . they are by their positioning electrically isolated from each other . each patch is configured and positioned so as to leave a border between its periphery and that of the underlying sensor element so as to avoid any possibility of electrical shorting at the periphery of the sensors . the outer portion of each foil strip , inwardly adjacent the end part , is interconnected with output wires 19 by conductive adhesion , as by soldering 20 . normally piezoelectric sensing elements may not effectively be directly interconnected with output wires because of the difficulty of forming an electrically interconnecting bond , the physical damage that might be done by the wires to the sensing elements especially as enhanced by any flexion of either element , and the electric noise generated by such an interconnection . encapsulation member 11 provides electrically insulative polymeric material 22 of a sheet - like nature extending about the sensing element to completely cover it . the encapsulating material provides both physical and electrical protection for the sensing element but must be sufficiently deformable to allow that element to flex without any substantial hindrance . the exact configuration and dimensioning of the encapsulating material is not critical , but preferably its periphery is of the elongate rectilinear shape illustrated , with a length several times its width and overall length approximately thirty percent longer than the length of sensing elements . normally the encapsulating material will comprise one of the neoprene polymers or something similar . it may be established about the sensing element by molding , adhesion or other similar processes well known in the plastic arts . support structures 12 comprise semi - rigid supports 23 , less deformable than the encapsulation member , carried on the same side of the encapsulating member 11 at each of its end parts . the exact shape and configuration of supports 23 is not particularly critical , but they normally will be formed of foamed polymeric material somewhat wider and somewhat thicker than the encapsulation member to properly position the sensing element and assure that the supports have somewhat greater rigidity . the supports extend inwardly sufficiently to provide a surface of some substantial area to allow connection with the encapsulation material and a human body , but yet leave a substantial space between the supports where the medial switch portion may flex . normally in a sensing device having an elongate dimension of approximately three inches , these supports should have an elongate dimension of approximately one - half inch . again , preferably but not necessarily , the dimensioning and arrangement of output wires 19 and metallic foil strip 17 is such that the interconnections occur adjacent one of the supports so that this interconnection will not flex so readily as if the area were located between supports . each support 23 is mechanically interconnected to the adjacent surface of the encapsulating member by adhesion , with adhesive film 24 communicating therebetween . this adhesive is such as to create a releasable bond that allows the adhered elements to be separated if desired . the outer surface 25 of each support , that is the one most distal from the encapsulation , is provided with a similar layer of adhesive to releasably bond with the skin of a human . this later adhesive must adhere to human skin but yet release therefrom without causing damage and must not irritate or harm the skin to which it adheres . the common latex - type adhesives or adhesives used on surgical tapes are quite well adapted for this purpose . generally both adhesive layers carried by the supports are of the same type , so that either adhered element may be removed without damaging the surface to which it is adhered . electrical circuitry 13 , of a type commonly used with our sensor , is illustrated in normal symbology in fig6 of the drawings , wherein various functional units of the circuitry are indicated in dotted outline to aid understanding . in the circuitry , the output of sensing device 10 is input through leads 26 from which the signal passes to comparator 27 which compares the input signal magnitude to a voltage reference and outputs a signal when the input voltage exceeds the reference voltage . the output signal then passes to activate indicator light circuitry 28 to annunciate the input and thence through switch 29 which allows selection of various other annunciative functions such as to activate a relay or an audible annunciator . the relay circuitry passes through leads 30 to relay switch 31 from whence the output is taken off through connectors 32 to operate separate circuitry ( not shown ). buzzer output from switch 29 passes through lead 33 to counting circuit 34 which requires a certain number of successive input signals for activation , each of which is indicated by indicator light circuit 28 . the signal passes conditionally , if the input limitations are met , to timing circuitry 36 which requires a predetermined number of input signals to be presented within a predetermined time interval . if this condition be met , the event is annunciated by light 35 and current is passed to timing circuit 37 which activates buzzer - type annunciator 38 to provide an audible response upon receipt of an appropriate signal . battery tester 39 is provided to annunciate through indicator light 40 to visually indicate battery condition of the device , which is powered by an ordinary nine volt storage battery ( not shown ). though specific electronic circuitry is shown in the diagram of fig6 obviously the functions described may be accomplished by many and various circuits other than those shown . the circuitry is not new per se and is not essential in any particular form to the operation of our sensor , though normally some amplification of a signal must be accomplished before it may be readily used . other electrical circuits heretofore known may well serve the ends of our invention . firstly , a switch is constructed according to the foregoing specifications and interconnected with appropriate electrical circuitry , such as that described , to make use of its electrical output . normally after manufacture , adhesive on the outer surfaces of supports 23 is covered by some protective membrane , and if this be the case , the membrane is removed to expose the adhesive and render it ready for use . the switch is then manually manipulated to position it , with some pressure , on two spaced portions of the human body that may be moved voluntarily relatively to each other to cause some flexion in the sensing element extending between the supports . this positioning may be accomplished such as over the skin adjacent an eye , the skin adjacent the mouth , the skin adjacent various joints in fingers or toes or elsewhere on the body where spaced portions may be relatively moved . the movement required actually is quite slight , as the switch is most sensitive and its sensitivity may be regulated by appropriate amplification of its signal . the switch may be adhered to the body at the desired position by manual pressure on the encapsulation material adjacent the support elements to cause the adhesive carried by a support to adhere to the skin . normally once adhered the device will remain in place for substantial periods of time and generally until manually removed . the adhesive attachment of supports to the encapsulation member allows support replacement when required especially as for sanitary reasons . once the switch is so positioned , the portion of the body involved may be appropriately moved to cause some flexion in the encapsulation member embodying the switching element . when this occurs , an electric current will be generated by reason of the piezoelectric activity of the sensor element , principally because of the stretching or stressing of its structure . the signal is received by the associated electric circuitry , amplified and put to use thereby either in activating a switching relay or operating some sort of annunciator . the switch , after its use be completed , may be removed by ordinary manual manipulation . preferably , an adhered surface is rather rolled from the skin , the sensor covering , or both to avoid and severe stressing or stretching of the sensing element which could cause permanent damage to it and cause it to lose its sensitivity . our switches normally may be used for long periods of time , if not indefinitely , so long as they are not physically damaged by external forces . the foregoing description of our invention is necessarily of a detailed nature so that a specific embodiment of it might be set forth as required , but it is to be understood that various modifications of detail , rearrangement and multiplication of parts may be resorted to without departing from its spirit , essence or scope . having thusly described our invention , what we desire to protect by letters patent and