Fabrication and characterization of silicon nanowires for pressure sensing applications

Abstract

Nanostructures made from crystalline silicon, especially in the form of nanowires (SiNWs), have shown great potential as pressure sensors due to their unique properties such as high sensitivity, small size, and low power consumption. When a force is applied to SiNWs, they undergo a mechanical deformation that results in a change in their electrical resistance. Such an effect has been referred to as the piezoresistance effect. This change in resistance can be measured and used to determine the amount of pressure being applied. By integrating these nanowires into a sensor device, it is possible to create a highly sensitive pressure sensor that can be used in a variety of applications such as in medical devices, aerospace technology, and robotics. Many available techniques can be applied to fabricate such SiNWs. One of the simplest ones is the so-called metal-assisted-chemical-etching (MACE) which has gained significant attention in recent years. This process involves the use of a metal catalyst, such as silver, to etch silicon in a controlled manner to produce nanowires with high aspect ratios. The nanowires can be integrated with other materials to create a flexible and stretchable sensor that can conform to curved surfaces and be used in a variety of applications. One advantage of using MACE to fabricate silicon nanowires is that it is a low-cost and scalable process. This makes it possible to produce large quantities of nanowires at a low cost, which is important for commercial applications. This thesis describes the fabrication of SiNWs using MACE and applications of the SiNWs as an accurate and sensitive pressure sensor for an isostatic and uniaxial load. Its use was further extended to fabricate a novel, small, and compact, breath sensor that could potentially have an impact on sleep research.