Patent Application
20140134053
The present invention relates to a portable electronic device such as a mobile phone, tablet and the like with an integrated chemical sensor being located within a duct through the exterior shell or housing of the device.
Portable or mobile devices originally introduced as mobile phones or electronic agendas become more and more ubiquitous. As the processing power of their internal processors grows and equally the bandwidth for communication with stationary processors, such portable devices take on more and more the role of multi-purpose tools available to consumers and specialist users alike.
It has been recognized that portable device can benefit from the presence of sensors capable of providing a chemical analysis of materials brought into contact or the vicinity of the device. Whilst there are many possible applications for such sensors, it suffices to consider for example the analysis of air surrounding the portable device. Such an analysis can be useful for multiple purposes such as testing for hazardous gases, breath analysis for general medical purposes or driving fitness, and the like.
However chemical sensors can often be rendered inefficient by lack of exchange of the medium to be analyzed, i.e. the analyte, within the immediate vicinity of the sensor. It is therefore seen as an object of the present invention to improve this exchange and hence prevent or reduce effects caused by saturation or stagnant flow.
Hence, according to a first aspect of the invention, there is provided a portable electronic device, preferably with telecommunication capabilities to allow for data and/or voice communication via private or public networks, enclosed in a housing having an air duct with an opening to the exterior of the housing and a chemical sensor with the duct connecting the chemical sensor to the outside and being linked with an actuator to move air along the duct and thus along a sensitive surface of the chemical sensor.
The portable device can be a smart phone, a handheld computer, a laptop, an electronic reader, a tablet computer, a game controller, a pointing device, a photo or a video camera, or a computer peripheral. Its housing is typically a shell of metal, glass, or plastic material and can be assembled as a unibody or from several parts. Enclosed in the housing are typically processors, drivers for parts such as screens, antennae, cameras, microphones and speakers as well as batteries to provide power to the device and its parts. A screen is typically arranged as a part of the housing or mounted behind a transparent window of the housing.
The duct acts as confinement for the air inside the housing and can take the shape of a tube or channel formed as part of the housing or as a separate part connected to an opening in the housing. It can be a single straight or curved duct. The duct can be connected to more than one opening in the housing and can for example terminate at two ends with openings in the housing. The duct can further branch into several ducts or cavities, in which an actuator or a sensor may be located.
The opening itself can be a dedicated opening thus exclusively connecting the chemical sensor to the outside. However, given that the manufacturers of portable electronic devices strive to maintain the housing as a good protection against humidity and water, it is seen as advantageous that the opening is shared with at least one further component of the portable device requiring a similar connection to the exterior, such as a loudspeaker, a microphone or a camera. The opening can further be protected by a grill or a membrane to prevent bigger particles or unwanted components of the air from entering or blocking the duct.
The chemical sensor may be understood as a sensor device for detecting one or even more properties of one or more analytes. It is preferably based on one of the following measurement principles:
The sensor can be based on a chemomechanical principle, in which a chemical reaction is transformed into a surface acoustic wave, or into a cantilever resonance, for example. Alternatively, there may be thermal sensing concepts applied, e.g. by making use of pellistors which may serve as a catalytic thermal sensor in which heat is generated during combustion. Alternatively, the chemical sensor may rely on optical detection, such as in form of a microspectrometer, or an NDIR, or may make use of electrochemical reactions such as being enabled by solid state electrolytes in combination with voltammetric, potentiometric, or conductometric measurement principles. Chemiresistors may also be used, such as conducting and carbon-loaded polymers, preferably in a low-temperature arena, or, more preferably, metal-oxide sensors such as tin oxide, tungsten oxide, gallium oxide, indium oxide, zinc oxide, which preferably may be applied in a high temperature environment. ISFET (ion-selective FET) may also be used, as well as chemocapacitors wherein it is preferred to use a polymer as active material.
The sensor includes the sensor material, preferably in form of a layer, also denoted as receptor layer, to which an analyte may bond to and as such modify an electrical property of the sensor material such as its electrical conductance, which principle preferably is applied in metal oxide chemical sensors, or an optical property such as its transmission rate. It can also include a plurality of different sensors or an array of similar sensors. In such a sensor array, each sensor cell may provide a layer of a material exhibiting different absorption characteristics such that each cell of the sensor array may specifically be sensitive to a different analyte and as such may enable the portable electronic device to detect the presence or absence or concentration of such analyte.
The actuator linked to the duct can be any device capable of accelerating or stopping the air within the duct at least locally, i.e. close to the sensitive surface of the sensor. The driving force of the actuator can be selected from a group including electromagnetical, mechanical, electro-acoustical or differential pressures, piezoelectric, heat or cooling. Due to the space constraints in most portable electronic devices, it is preferred to make use of an actuator, which is not exclusively dedicated to the operation in conjunction with the chemical sensor but instead has at least a dual function providing a force used for other components of the portable device.
The above and other aspects of the present invention together with further advantageous embodiments and applications of the invention are described in further details in the following description and figures.
The device of
Another opening 106 is located at the lower side wall. As shown in
In the example the chemical sensor is a gas sensor using a metal-oxide layer mounted onto and integrated with a CMOS substrate. The metal-oxide used can be tin oxide, tungsten oxide, gallium oxide, indium oxide, or zinc oxide. For particular embodiments as described in further details below the sensor can also include a micro electro-mechanical system or MEMS type heat source integrated within the sensor.
In the first series of examples illustrated in
For example in
The example of
In the example of
In the example of
In the second series of examples illustrated in
In the example of
It can be further advantageous to drive the general purpose loudspeaker 33 with a specific signal designed to increase the movement of air over the surface of the sensor. For example, a signal can be used which causes the emission of a sequence or wave train of very low frequency or bass sounds. It is also possible to enhance the effect of an acoustic signal by exploiting resonance frequencies such as the resonance frequencies of the air column in the duct 31 and drive the loudspeaker or any other wave source at or close to such a resonance frequency.
In the variant of
In
In the examples above the transducer is placed in close proximity of the chemical sensor. However, as long as the motion of the actuator is transferred to the air in the duct, such a co-location of sensor and actuator is not required and the position of the actuator can be chosen more freely within the housing to make better use of the available space within the housing of the portable device.
In the third series of examples illustrated in
In the convection process a heat source generates an air flow in the duct with the sensor. In the example of
The principles of these MEMS-type hot-plates manufactured using CMOS or other semiconductor fabrication methods can be applied to or used in conjunction with any chemical sensor in order to provide a heat source for convection with the duct 41 inside the portable device.
While for a typical metal-oxide sensor the heat source is necessarily located close to the actual sensor, in general the heat source for generating convection can be placed anywhere along the duct or close to it. The heat source is thus not necessarily a part of the sensor but can be a dedicated heat source using for example resistance heating, electro-thermal or Peltier effects or a MEMS-type hot plate on a dedicated chip or substrate. Such a dedicated heat source can be placed at any appropriate location along the duct for optimized convection.
The convection process can also be driven using excess heat from any of the standard components of the portable device. It is known that the processors used in such devices generate excess heat which needs to be dissipated to the exterior to avoid overheating of the device. The process can be exploited to carry excess heat through the duct 41 as shown in
The convection over the sensor 42 can be further improved if at least part of the duct 41 is oriented upwards so as to provide an effect similar to a chimney. Thus the heat source 43 can be controlled using position information as provided by other components of the portable device, for example by accelerometers or gyroscopes. With such a control, the heat source is activated when the orientation sensor signals a suitable orientation of the portable device and, hence, of the duct 41. In
Alternatively or in addition, the measuring process itself can be controlled using orientation information. For example it is possible to activate the chemical sensor for a (valid) reading or measurement only in predefined positions or orientations.
It is also possible to use the thermal expansion of air over the heat source as driving force to exchange air in the vicinity of the sensor. In such an application the heat source is best operated in an AC or a pulsating mode such that the periods of expansion of the air volume are followed by periods of contraction, effectively pumping new air into the volume above the sensor.
It is further possible to use two or more of the actuators as for example described above in combination to enhance the air flow at the location of the chemical sensor 52. In
As already mentioned above in connection with the orientation of the phone, the operation of the actuator and/or sensor can be controlled depending on a state of the portable device in general such as orientation, battery charge status, accidental blockage of the openings, and other states, which influence the performance of actuator and/or sensor. In these cases the control can initiate, interrupt, and end the operation of the sensor and/or actuator when the status of the portable device is not suited or ready for a satisfactory measurement.
In the example of
While there are shown and described presently preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practised within the scope of the following claims.
