SBIR-STTR Award

The objective of this research is to design a micromechanical temperature sensor capable of recording temperature extremes experienced beyond a preset value without the use of electrical power. The temperature sensor's memory will be mechanically induced. The sensor will be either in an electronically resettable form, or, less expensively, in a disposable form. The proposed device will be microfabricated using integrated circuit(IC) and silicon micromachining techniques. As a result, the sensor will be electronically readable, inexpensive, and small. Anticipated

Benefits:
The sensor can be used in applications in which power source usage is impractical (e.g., in mobile personnel) and where expense must be limited (e.g., in shipping containers). In DoD applications, the proposed microsensor can be used for monitoring temperature exposure of personnel, food, and medical supplies in the field. Since the sensor will be small, it is well suited for such applications in which weight and size of added instrumentation is critical. Additionally, the sensor has many private sector applications; for example in shipping and tire industries.

We propose a focused program for the development of micromechanical sensors capable of recording temperature extremes beyond a preset value without requiring a power source. The sensors incorporate a micromechanical latch which acts as a one-bit memory. The state of the latch, and therefore the sensor, is electronically readable. The latch may be fabricated such that it is electronically resettable. The latching mechanism consists of two overlapping, bimetallic cantilever beams microfabricated using integrated circuit (IC) processing and silicon micromachining techniques. The latch is triggered thermally when a temperature change beyond a preset value causes the bimetallic beams to bend beyond a threshold limit, and therefore requires no electrical power during operation. Since the sensors are microfabricated using IC fabrication and micromachining processes, they are small and inexpensive. Such sensors are ideally suited for temperature monitoring applications where low cost and small size is important, and where an electrical power source is not readily available. Such a class of micromechanical temperature memory sensors (hereafter "MTMS") has significant dual use applications with large markets. The MTMS is competitive in a $30 million market for monitoring the temperature exposure of perishable goods during transportation and storage, and as a component in a 'smart tire' monitoring system under development by Goodyear Tire and Rubber Company. Other applications include medical monitoring, consumer electronics, and monitoring of temperature sensitive goods during storage.