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Silicon nanowire (SiNW) has received great attention in sensing applications because of its outstanding piezoresistive (PZR) effects. However, the difficulty of integrating SiNWs and sensor structures has hindered the development of various SiNW-based sensors. This paper presents a new simple, scalable fabrication method for SiNWs and its application to accelerometers. The developed method enables monolithic integration of SiNWs with sensing structures and allows controlling the dimensions of SiNWs and sensor structures independently. Furthermore, the developed method has significantly reduced fabrication complexity when compared to the previous approach by reducing the number of mask layers. In this paper, a SiNW-based PZR accelerometer is fabricated using the developed method, and experiments are performed. Compared to commercial capacitive accelerometers, the presented PZR accelerometer can reduce approximately 36 % of the total area by replacing the comb-type capacitive sensing units by much smaller SiNWs.

Silicon nanowires (SiNWs) have received attention in recent years due to their anomalous piezoresistive (PZR) effects. Although the PZR effects of SiNWs have been extensively researched, they are still not fully understood. Herein, we develop a new model of the PZR effects of SiNWs to characterize the PZR effects. First, the resistance of SiNW is modeled based on the surface charge density. The characteristics of SiNW, such as surface charge and effective conducting area, can be estimated by using this resistance model. Then, PZR effects are modeled based on stress concentration and piezopinch effects. Stress concentration as a function of the physical geometry of SiNWs can amplify PZR effects by an order of magnitude. The piezopinch effects can also result in increased PZR effects that are at least two times greater than that of bulk silicon. Experimental results show that the proposed model can predict the PZR effects of SiNWs accurately.

This paper presents the piezoresistive (PZR) effects of silicon nanowires (SiNWs) and evaluates the possibility of using them in biomimetic sensors. SiNWs have greatly enhanced PZR effects compared to bulk silicon. Their structure can be fabricated to resemble that of receptor cells to mimic their functions. In this paper, SiNWs are fabricated through a new microelectromechanical systems (MEMS) process. The developed process can independently control the width and thickness of SiNWs. The PZR effects of the fabricated SiNWs are measured using a four-point bending technique. They increase as their dimensions decrease, but change as a nonlinear function of the SiNW cross-section dimensions.

Recently, biomimetic robots have received great attention as an alternative to overcome the limit of conventional robots. However, there is no standardized methodology to design and determine the specifications of biomimetic robots. In this paper, the concept of allometric scaling and its application to biomimetic robot design considerations are discussed. Also, characteristics of motion data of small insects and animals, which are eight species of crawling and eight species of flying creatures, all with less than 400 g in weight, are investigated. These are used to compare with those of recently presented biomimetic robots as a function of the body mass in several categories, including the velocity, angular velocity, acceleration, stride frequency, and wing beat frequency. The results show that the characteristics of most of the small biomimetic robots approximately fit in the allometric scaling of insects and animals. However, it is found that some small robots have characteristics which are quite different to those predictable from the allometric scaling law. Learning from nature may be a solution to design and determine the specifications of biomimetic robots, and the allometric scaling can be the one of the methods that can help define the achievable performance envelope.