Embodiments of the present disclosure relate generally to methods and apparatus for monitoring temperature, humidity, and/or other environmental or chemical analog variables. More particularly, although not exclusively, these embodiments are concerned with the detection of product abuses such as spoilage and/or the detection of the level of freshness or environmental abuses of products, equipment or consumable items.
As an introduction to the problems solved by the present application, it is generally desirable in the art of making smart labels and smart packaging products to be able to measure the integral of temperature, humidity, or other variable over time. Such an integration measurement can be used to indicate a degree of exposure to undesirable environmental conditions. Time-Temperature Integration (TTI) and Time-Humidity Integration (THI) are two such valuable metrics used to determine product abuses or levels of freshness.
To accomplish such measurements, it is known in the art that a high degree of accuracy can be obtained using an Analog to Digital Converter (ADC), together with a processing logic unit that performs floating-point algorithms. Alternately, a microprocessor, a Programmable Logic Device (PLD) or a Digital Signal Processor (DSP) type of processing platform can be used.
When considering the cost of goods required to build such processing circuitry into smart labels and smart packages, even at the smallest levels of integration (deep sub-micron), using fully custom Application Specific ICs (ASICs), the cost of goods is too high to be applicable in a typical packaging situation. Cost sensitivities drive the need for lower-cost and lower-power circuitry for smart label and smart packaging devices.