Reaction with transduce inserts

Fig. 7.19. Reaction tube with transducer inserts in a spiral configuration.

Instead of immobilizing the antibody onto the transducer, it is possible to use a bare (amperometric or potentiometric) electrode for probing enzyme immunoassay reactions (42). In this case, the content of the immunoassay reaction vessel is injected to an appropriate flow system containing an electrochemical detector, or the electrode can be inserted into the reaction vessel. Remarkably low (femtomolar) detection limits have been reported in connection with the use of the alkaline phosphatase label (43,44). This enzyme catalyzes the hydrolysis of phosphate esters to liberate easily oxidizable phenolic products. 

Fig. 3.1 Setting-up and tuning an ultrasonic bath for use in zinc insertion, (a) The ultrasonic bath immediately after switching on. Note the intense disturbance above each of the two transducers, (b) At this point, the surface of the water has settled, but the two positions of maximum agitation are still distinct, (c) Placing the empty flask in the bath results in a smooth water surface, apart from the point immediately above the second transducer, (d) Optimum conditions for ultrasonic zinc insertion are shown here, with a perfectly smooth water surface, and significant frothing in the reaction flask.

The dynamic distributed load that corresponds to the vertical ground reaction force can be evaluated with the use of a flat, two-dimensional array of small piezoresistive sensors. OveraU resolution of the transducer is dictated by the size of the individual sensor ceU. Sensor arrays configured as shoe insole inserts or flat plates offer the clinical user two measurement alternatives. Although the currently available technology does afford the clinical practitioner better insight into the quahtative force distribution patterns across the plantar surface of the foot, its quantitative capabiKty is limited because of the challenge of caKbration and signal drift (e.g., sensor creep). 

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