The present disclosure is related to sensing methods, and more specifically to a method by which an electronic device formed by printing senses shock, inertial movement, pressure force, presence of light, chemicals, biologics, etc. and generates an electric pulse which is indicated on a dedicated display.
There are today a relatively large number of different techniques for producing electronic devices. One family of such techniques, of interest herein, is commonly referred to as printed electronics. Various methods fall within the definition of printed electronics. Screen printing, traditional and digital lithography, flexography, gravure and jet-printing are a number of the more common of such methods. In each case, a material, conductive, semi-conductive or insulating, is deposited over a substrate to form interconnected passive and and/or active electronic components. Printing processes typically deposit materials in form of a solution, a slurry or in form of a powder. However, also transfer processes such as thermal transfer or laser transfer processes may be used to print structures. In a thermal transfer process, a layer such as a metal film may be transferred from a carrier substrate to another substrate. Known printed electronic processes can utilize a wide variety of materials for these components, and are not limited to organic materials.
Printed electronic processes take advantage of known, relatively simple printing techniques, and are thus typically less expensive and often less environmentally hazardous than traditional lithography and deposition techniques. Certain materials and processes used for printed electronics permit printing on non-crystalline substrates, such as paper, plastic, fabric, etc. Such processes may permit printing on flexible substrates, which is not easily done with conventional electronic device fabrication techniques. Furthermore, printing processes have been developed for non-planar surfaces, which is also a challenge for conventional electronic device fabrication techniques. However, in order to maintain a low cost and/or substrate flexibility, the components produced by printed electronic processes are relatively large, and the circuits relatively simple. For this reason, and others, printed event sensor devices are not generally available today.
An event sensor, as used herein, is a device for detecting and indicating the occurrence, duration, and extent of an event or a series of events. Sensed events include acceleration, pressure force, exposure to light or other radiation, sound, and so forth. A relatively common event sensor is the accelerometer. Conventional accelerometers are typically based on mechanical or electromechanical components. For example, when a “proof” mass within the sensor is displaced, such as by acceleration or deceleration, often referred to as shock, that displacement is measured, and a signal issued in accordance therewith. More compact devices rely on strain gauges, in which current through a member is a function of the strain it experiences, micro-electro-mechanical (MEMs) devices, which are often very small proof masses, interleaved combs, and the like, and piezoelectric materials, in which strain results in generation of a charge within the material. The sensing signals issuing from these devices are commonly processed by additional electronic circuits for amplification, processing, display, and so on.
The applications for event sensors vary widely. However, a common requirement for many applications is low cost. There is a further common requirement for many applications that the sensor and even the display mechanism be flexible, for example permitting it to be applied over a non-planar structure, such as a medicine bottle, shipping package, etc. Still further, in some applications it is desirable to provide a sensor without a separate voltage source (e.g., without a battery).
Present event sensors are not capable of meeting these requirements. The majority of known systems do not provide both a low cost sensor and a low cost display in a single circuit. Furthermore, most low cost shock sensing systems are configured to indicate whether a threshold level of shock has been exceeded. Still further, common shock sensing systems do not provide field replaceable elements such as display portions and the like. And common electronic shock sensors require a battery or similar separate voltage source.