by way of example only , certain preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings . referring to fig1 the testing device of the present invention is shown as configured for the detection of fecal occult blood in stool by immunochromatographic methods . fig1 a shows the device of the present invention with a front panel cover ( 10 ) comprising two sample application cover flaps ( 11 and 13 ) in the closed position . by raising flap ( 11 ), a patient exposes a first sample application aperture ( 14 ) in the front panel ( 17 ) of the device ( fig1 b ). the first sample application aperture is in communication with a sample application matrix ( 18 ) ( shown in fig4 ). sample is applied to the sample application matrix ( 18 ) via the sample application aperture ( 14 ). following application of the sample , cover flap ( 11 ) is closed and sealed . a pressure sensitive adhesive with a removable backing strip ( 19 ) is provided for this purpose . the process is then repeated on a second consecutive day and sample is applied via the sample application aperture located behind flap ( 13 ). while the embodiment shown in fig1 a and 1b has only two sample application apertures , this is intended to be non - limiting . the sealed testing device is then forwarded to a doctor &# 39 ; s office or testing laboratory for determination of test results . upon receipt , a technician at the doctor &# 39 ; s office or testing laboratory opens the testing window ( 25 ) located on the rear panel cover ( 23 ), as shown in fig2 a . perforations are provided for the opening or removal of the testing window to facilitate access . opening or removal of the testing window ( 25 ) reveals several apertures which characterize the rear panel ( 16 ). these include solvent application apertures ( 27 and 29 ) and testing element insertion aperture ( 31 ). a testing element ( 33 ) is then inserted into the testing element insertion aperture ( 31 ). the testing element ( 33 ) contains a reagent enabling the detection of the analyte of interest in the sample . the testing element is shown in exploded cross - section in fig3 . the testing element is comprised of a liquid - conductive solid phase material ( 35 ) which is preferably nitrocellulose membrane . to facilitate handling , a backing sheet ( 39 ) is provided . non - absorbent plastics such as lexan or polystyrene are preferred backing sheet materials . preferred embodiments also include one or more layers of high capacity liquid conducting material referred to herein as “ bridging layers ”. a bridging layer ( 38 ) is shown in fig3 . in the embodiment of fig3 a conjugate pad ( 37 ) is disposed between bridging layer ( 38 ) and the liquid - conductive solid phase material ( 35 ). as discussed above in connection with preferred immunochromatographic embodiments , the conjugate pad contains labelled detection reagent desiccated in situ . an absorbent pad ( 41 ) is also provided as a component of testing element ( 33 ). the absorbent pad ( 41 ) functions as a solvent sink thereby driving the migration of the solvent front . the elements shown in fig3 are assembled using a non - water soluble adhesive . it will be evident that the overlap of elements such as bridging layer ( 38 ) and conjugate pad ( 37 ) creates a progressive wedging effect which results in good liquid conductive contact between the sample application matrix ( 18 ) and the testing element ( 33 ), following insertion of the testing element ( 33 ) into the testing element insertion aperture ( 31 ). immobilized capture reagent is attached to the liquid - conductive solid phase material thereby creating a detection zone ( 43 ) on testing element ( 33 ). fig4 is a cross - section of the device with the testing element ( 33 ) inserted . fig4 shows many of the previously discussed elements including , for example , testing element ( 33 ) and individual components thereof ( absorbent pad ( 41 ), liquid - conductive solid phase material ( 35 ), conjugate pad ( 37 ), bridging layer ( 38 ) and backing sheet ( 39 )); sample application cover flap ( 13 ); front panel ( 17 ) with sample application aperture ( 15 ); rear panel ( 16 ); rear panel cover ( 23 ) with testing window ( 25 ); and sample application matrix ( 18 ). also shown is an optional element not previously discussed . this optional element is referred to as a spacer panel ( 42 ). the spacer panel , which is shown in greater detail in fig5 functions to create a testing element insertion void space between the sample application matrix ( 18 ) and the front panel ( 17 ) in the assembled device . spacer panel ( 42 ) includes a second testing element insertion aperture ( 44 ) and embossed point ( 48 ), also shown in fig5 . as shown in fig4 when testing element ( 33 ) is inserted , it occupies this testing element insertion void space . the progressive wedging referred to previously in connection with fig3 results in good liquid - conductive contact between the sample application matrix ( 18 ) and the testing element ( 33 ). again referring to fig4 following insertion of the testing element , the technician rehydrates the sample by adding a solvent to the sample application matrix ( 18 ) via solvent aperture ( 29 ) in rear panel ( 16 ). the solvent solubilizes sample components in the sample application matrix ( 18 ) and carries the solubilized components through bridging layer ( 38 ) and into the conjugate pad ( 37 ) with the solvent front . in the conjugate pad ( 37 ), labelled detection reagent is solubilized and binds to analyte if present in the sample . the solvent front , and any soluble materials carried with the solvent front , then move on to the liquid - conductive solid phase material ( 35 ). if analyte is present in the sample , a visibly detectable complex comprising analyte , labelled detection reagent and immobilized capture reagent forms in detection zone ( 43 ). in a preferred embodiment , front panel cover ( 10 ), rear panel cover ( 23 ), front panel ( 17 ), rear panel ( 16 ) and spacer panel ( 42 ) are produced from a single sheet of stock by appropriate cutting and folding . referring to fig5 a generally rectangular sheet of stock is provided . solvent application apertures ( 27 and 29 ) and a testing element insertion aperture ( 31 ) are cut in rear panel ( 16 ). sample application apertures ( 14 and 15 ) are cut in front panel ( 17 ). the outline of the diagnostic window ( 25 ) is perforated in the rear panel cover ( 23 ). the front panel cover ( 10 ) is cut to form two flaps ( 11 and 13 ) which will seal the sample application apertures following sample application . pressure sensitive adhesive ( 19 ) is provided for sealing sample application cover flaps ( 11 and 13 ). spacer panel ( 42 ) is cut to provide a second testing element insertion aperture ( 44 ). in addition , the spacer panel ( 42 ) is optionally embossed at embossed points ( 46 and 48 ). as an alternative to embossed points ( 46 and 48 ), optional spacer elements may be attached to spacer panel ( 42 ) using an adhesive . the function of the optional embossed points ( 46 and 48 ) or the alternative optional spacer elements , is to increase the testing element insertion void space between the sample application matrix ( 18 ) and the front panel ( 17 ) in the assembled device , if desirable . whether or not to include such optional elements depends , for example , on the relative thicknesses of the sample application matrix ( 18 ) and the stock from which the housing is produced . folds are made along lines d — d , c — c , b — b , and a — a to form the housing . prior to folding , the sample application matrix is appropriately positioned and adhesive is applied in appropriate locations to aid in maintaining the relationship of elements in the folded housing . test elements were manufactured by laminating the following components to a white plastic support ( high impact polystyrene , 0 . 5 mm ), coated on one surface with adhesive ( 3m , st . paul , minn ., # 465 transfer tape ), as shown in fig3 : 1 ) nitrocellulose membrane ( millipore , bedford , mass ., type sthf0200 , 18 mm ) striped with monoclonal anti - human hemoglobin antibody at 2 mg / ml ; 2 ) absorbent for absorbent pad ( ahlstrom , mt . holly spring , pa ., grade 904 , 18 mm ); 3 ) conjugate pad ( general polymeric , reading , pa ., 25 micron uhmwpe skived tape , 10 mm ) infiltrated and dried in situ with polyclonal anti - human hemoglobin antibody conjugated to colloidal gold ( ey laboratories , san mateo , calif . ); and following lamination , the web was slit at 6 mm intervals to form individual test elements . housings ( 73 mm × 76 . 2 mm ), as depicted in fig5 were manufactured from waterproofed ( polycoated ) sbs cardboard . the sample application matrix ( porex , fairburn , ga ., hdpe type 4588 ) was applied to the rear panel of the housing with transfer adhesive ( 3m , # 465 ). human blood was diluted 1 : 10 , 000 and 1 : 100 , 000 in distilled water . for each of the dilutions of blood , and for a control sample of distilled water , 25 μl was added to each of the two sample application apertures of a testing device and allowed to air dry for two hours . 100 μl reconstituting reagent ( p . b . s . containing 0 . 5 % bovine serum albumin , 1 % triton x100 and 0 . 1 % sodium azide ) was added to each solvent application aperture and a test strip inserted . a clear red line developed on the test strip with the two blood dilutions , i . e . positive detection , whereas the water sample gave no detectable signal ( i . e . a negative result ). in an otherwise identical experiment , the same blood dilutions were added ( 25 μl for each ) to hemoccult ( smithkline diagnostics , palo alto , calif .) slides and a colocare ( helena laboratories , beaumont , tex .) test pad ( a device for detecting blood in the toilet bowl water that is added directly to the toilet bowl ). fresh human blood ( 50 μl ) was added to the water in a toilet bowl (˜ 2 l ). after full dispersion of the added blood , the water was sampled with a dacron swab ( hardwood products , guildford , me .) and transferred to a hemoccult card and a to the sample application matrix of the device of the present invention . following the sampling , a colocare pad was added to the toilet bowl and observed for any change in color . the device of the present invention readily detected the blood , whereas water taken from the bowl before the addition of the blood tested negative . the hemoccult and colocare tests remained clearly negative with the water to which the blood had been added .