Pseudo-Hall effect in graphite on paper based four terminal devices for stress sensing applications

A cost effective and easy to fabricate stress sensor based on pseudo-Hall effect in Graphite on Paper (GOP) has been presented in this article. The four terminal devices were developed by pencil drawing with hand on to the... [ view full abstract ]

A cost effective and easy to fabricate stress sensor based on pseudo-Hall effect in Graphite on Paper (GOP) has been presented in this article. The four terminal devices were developed by pencil drawing with hand on to the paper substrate. The stress was applied to the paper containing four terminal device with the input current applied at two terminals and the offset voltage observed at other two terminals (called pseudo-Hall effect). The GOP stress sensor showed significant response to the applied stress which was smooth and linear. These results showed that the pseudo-Hall effect in GOP based four terminal devices can be used for cost effective, flexible and easy to make stress, strain or force sensing applications. In recent years, researchers have paid much attention to paper based devices for diagnostics and electronic applications. Flexible and wearable electronics is the fundamental part of flexible appliances which require ultra-thin and flexible navigation modules, force sensing, body tracking, and relative position monitoring systems. Soft robotics and transient electronics are the ultimate beneficiaries of these flexible and wearable electronics. The main advantages of this technology are the low cost, diversity in material choice, disposability and ease of fabrication. Graphite on paper (GOP), in which graphite layers are deposited on paper by either graphite-ink printing techniques, or manual pencil drawing techniques, has been utilized as the sensing element in flexible sensors for strain. Most of the work on GOP based stress/strain sensors is based on the two terminal resistor sensors which suffer several drawbacks. They show high temperature sensitivity relative to stress response and require Wheatstone bridge to detect the signal. On the other hand pseudo-Hall effect device inherently utilizing the high accuracy of four-wire resistance measurement method can overcome the limitations of the conventional resistor sensors. Therefore, in this study we report a GOP based cost effective and flexible stress/strain sensor based on pseudo-Hall effect. We have investigated the response of GOP four terminal devices and results are shown in Fig. 1(i). The smooth and linear behavior of the device against applied stress shows its potential applications in stress/strain and force sensing applications.