Non-electrical sensing and storing an alternative to electrical energy harvesting
In many applications, a summarized result, e.g. the number of critical off-limit conditions or an integral result over a specific period of time are of interest to draw implications for the future. Among these applications are the shelf life monitoring of consumables, pharmaceutics or food as well as the condition monitoring of technical infrastructure. Sensors usually require an electrical energy source for measurement and storage of data. Here, two non-electrical examples are presented that register data without the need of electrical energy: a passive temperature-time integrator (TTI) and a mechanical binary counter for threshold events. The TTI makes use of microfluidic flow of specific food ingredients into microcapillaries that depends on viscosity and time. The binary counter based on surface MEMS allows counting and storing threshold events, e.g. mechanical shocks. Both sensors can easily be read out e.g. by RFID.