Nokia has pioneered the research on wonder material Graphene. A latest patent granted to Nokia reveals use of Graphene Oxide sensing film in protecting a battery-operated mobile device from water. The Graphene Oxide film senses moisture content or change in relative humidity just before getting in touch with water thereby triggering a disconnection of mobile device from power source (Battery). This can ensure that no mobile circuitry damage happens due to water.
Exemplary embodiments of a device for the protection of a battery-powered electronic device from water are disclosed herein. The device includes a sensor capable of sensing water in liquid or vapor form based on the measurement of very large time derivative values. The sensor comprises (i) a graphene oxide (hereinafter “GO”) thin film and (ii) two or more electrodes in contact with the thin film. An electronic switch is connected to the sensor and to a power source (e.g., the battery) that powers the circuitry in the electronic device. One possible trigger to activate the electronic switch to disconnect the circuitry of the electronic device from the power source may be a measured threshold value of the time derivative of the GO sensor signal.
In the exemplary embodiments of such a device, if the relative humidity suddenly increases up to high values (e.g., up to 90%, or higher than predetermined standard device operating conditions), the value of the electrical impedance of the GO thin film drops exponentially by several orders of magnitude and almost instantaneously. Such an instantaneous response translates into large values of the time derivative of the GO impedance, which makes the electronic switch disconnect the power source from the circuitry of the electronic device prior to the contact the circuitry by liquid water, thereby providing an ultrafast response time with regard to the sensing of water.
It also seems that integrating such a sensor in a mobile device can be very easy and it can just be coated on the battery.
The GO can be easily integrated into the sensor as a thin film by, for example, being printed on the power source. For example, the sensor may be integrated into a battery, e.g., by printing the GO film and the electrodes directly on a surface of the battery. In some exemplary embodiments, the film may less than about 100 nanometers (nm) thick. Due to the two-dimensional nature of GO (which is generally employed in flake form), a GO film having a thickness equal to few atomic layers could be achieved, e.g., by Languir-Blodgett deposition. Other exemplary methods by which the GO film can be formed include, but are not limited to, spray coating and spin coating. By employing such methods, the device can be manufactured at low cost.
In alternate exemplary embodiments, the sensor may comprise materials other than GO, such as graphene oxide, reduced graphene oxide, graphene, functionalized graphene, fluorographene, molybdenite, boron nitride, tungsten disulphide, combinations of the foregoing materials, and the like.
The technology in question can be clubbed with other water-proofing techniques or can be employed alone to enhance life of mobile devices at low-cost.
The exemplary embodiments of the apparatuses and methods pertaining to the sensor as disclosed herein can be advantageously considered complementary to other apparatuses and methods that prevent water damage of a mobile electronics device by water-proof encapsulation. Furthermore, the exemplary embodiments as disclosed herein may be used without specialized water-proof containers for a particular mobile electronics device, could be easily integrated with other mobile electronics devices at low cost, and could increase the lifetime of a mobile electronics device while reducing costs due to warranty claims for water damage. Moreover, the exemplary embodiments as disclosed herein could improve the robustness of mobile electronics devices and reduce chances of water damage occurring, thereby improving brand perception and trust.
