Abstract: A method is disclosed for detecting the occurrence of a binding or complex-forming reaction between specific substances by utilizing the binding reaction to modify an electrical circuit, and then measuring a change in the electrical state of the circuit. A diagnostic element useful in such a method includes a layer of a biogenic substance, such as an antigen, coated onto a non-conductive base between a pair of electrical conductors superposed on the base. Antibodies which react with the antigen are treated so that they become bound to particles. The particles having antibody bound thereto are then added to is the antigen lay e base and allowed to react therewith. The particles are thereby bound to the base due to the binding reaction between the antigen and antibody to thereby form aggregates of electrically conductive particles which modify the circuit. The particles are then selectively coated with a conductive substance.

Abstract: A method is disclosed for detecting the occurrence of a binding or complex-forming reaction between specific substances by utilizing the binding reaction to modify an electrical circuit, and then measuring a change in the electrical state of the circuit. A diagnostic element useful in such a method includes a layer of a biogenic substance, such as an antigen, coated onto a non-conductive base between a pair of electrical conductors superposed on the base. Antibodies which react with the antigen are treated so that they become bound to fine electrically conductive, metallic particles. The electrically conductive particles having antibody bound thereto are then added to the antigen layer deposited on the base and allowed to react therewith. Electrically conductive particles are thereby bound to the base due to the binding reaction between the antigen and antibody to thereby form aggregates of electrically conductive particles which modify the circuit.

Abstract: An erosion and corrosion resistant coating is formed of a plurality of alternating layers of metallic and ceramic materials. The two materials selected for the layers have complementary wear resistant characteristics, such that one is relatively ductile and the other is relatively brittle. The concentration of the two materials at the interface between adjacent layers is graded to improve the adhesion of the layers and to provide a more unified coating. Prefereably radio-frequency sputtering is employed to deposit the coating, since it does not produce excessive heating which could negate any prior heat treatment of the substrate onto which the coating is deposited.

Abstract: A method is disclosed for detecting the occurrence of a binding or complex-forming reaction between specific substances by utilizing the binding reaction to complete an electrical circuit, and then measuring a change in the electrical state of this circuit. In a preferred embodiment, a layer of antigen is coated onto a non-conductive base between a pair of electrically conductive layers superposed on the base. Antibodies which react with the foregoing antigen are treated so that they become bound to fine electrically conductive, metallic particles. The electrically conductive particles having antibody bound thereto are then added to the antigen layer deposited on the base and allowed to react therewith. Electrically conductive particles are thereby bound to the base due to the binding reaction between the antigen and antibody to thereby form aggregates of electrically conductive particles which bridge the electrically conductive layers and complete the circuit.