May 17, 2007 Urinary incontinence affects over 200 milion people worldwide, to varying degrees between "occasional accident" and "complete lack of control." The AssureFlow concept device acts as a manually switchable on-off tap for the bladder, providing dignity and control to incontinence sufferers in an ingenious way.

The AssureFlow, designed by Australian tertiary student Ms. Angelene Ozolins, is designed to act on behalf of the natural function of the bladder, both for those with weak bladders and for those who, through nerve damage or other conditions, lack the normal level of control.

It consists of two parts; an internal valve that is implanted in the urethra of the patient, and a hand-held actuator that uses inductive heat to turn the valve on and off.

The internal valve consists of three co-centric stent-like tubes. The two inner tubes are made of Nitinol, a shape memory alloy with the fascinating ability to become superelastic above a certain temperature or stress level, or harden at a lower temperature, which can be set depending on the levels of different metals in the alloy.

The two Nitinol tubes have different temperature and stress thresholds inherent in their material properties. The outer tube when heated to the body’s temperature turns rigid to its austenite state. This tube compresses the inner tube (which is still in its soft martensite state), and the silicone to form a watertight seal.

The inner tube has a higher temperature threshold. This tube (a coil to localise the energy) is heated via the external actuator (through inductance). When the inner tube is heated, it begins to expand. The stress of this tube expanding overcomes the austenitic state of the outer tube and applies enough stress to revert the outer tube back to its soft martensite state. Therefore the tube is able to be forced open and allow urine to pass.

When the heat from the external actuator is removed, the inner tube reverts back to its soft martensite state, and the outer tube becomes rigid austenite at the body’s temperature, closing the valve once again.

The hand-held actuator is small and discreet, requiring two buttons to be pressed simultaneously before it activates the valve. It also contains a USB port and memory which can be used to store information about the patient's voiding patterns.

Although this is currently just a concept design and finallist in the Dyson Australian Student Design Awards, it's a design that could make a very positive change in the lives of a large number of afflicted people.

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