Abstract
This paper reports on the controlled fabrication of a highly sensitive piezoresistive sensor by using Si nanorod (NR) arrays. An efficient, large-area, scalable strategy was adopted to fabricate the pressure sensors by incorporating chemically etched, high-aspect-ratio, vertical Si NR arrays between two thin Au layers. The piezoresistive properties corresponding to dimension- and position-controlled and randomly etched, closely packed, and thin Si NR arrays were exploited to fabricate the small, portable, and device-compatible pressure sensors. The Si-NR-based piezoresistive sensors exhibited a high sensitivity of 0.49 MPa −1 , thereby demonstrating its superiority over other unconventional piezoresistive nanomaterials such as Si with different configurations of nanostructures. Furthermore, the sensors exhibited a large variation (~45%) in the current at a constant bias voltage of 2 V under a weak applied pressure corresponding to an inert gas flow of 5 sccm. The excellent pressure sensing performance of the piezoresistive Si NRs enabled the efficient detection of changes corresponding to the human breathing pattern. In particular, the key advantages of such pressure sensors is the simple, inexpensive, and scalable fabrication process; high sensitivity with ultra-low-pressure detection; and excellent ambient stability (>several months) with a high durability pertaining to more than 1,000 cycles of pressure loading/unloading. Furthermore, we demonstrated the ability of the pressure sensor to act as a portable human breath sensor to monitor respiratory parameters in a noninvasive and personalized manner. The results can provide direction for the realization of next-generation breath-sensing gadgets and other leading-edge applications in the domain of electronic and healthcare devices. • Chemically etched, dimension- and position-controlled Si nanorod arrays are utilized as pressure sensors. • Piezoresistivity in mesoporous Si nanorod is revealed to achieve a high-pressure sensitivity. • The pressure sensor detects a tiny flow of inert gas efficiently. • Demonstrated the pressure sensor’s ability to act as a portable human breath sensor.
Highlights
Pressure sensors have attracted considerable interest owing to their potential for application in various areas including different industries, research domain, and environmental monitoring and human healthcare fields
Ag was used to fabricate the closely packed, thin Si NR arrays with a random size, the Si NRs prepared using the metal-assisted chemical etching (MACE) technique are mesoporous, with the porosity depending on the etching parameters
The selected area electron diffraction (SAED) pattern (inset of Fig. 1(e)) acquired from a single Si NR exhibited the polycrystalline nature of the Si nano-islands, even though the Si NRs were prepared from single-crystalline Si (100) wafer
Summary
Pressure sensors have attracted considerable interest owing to their potential for application in various areas including different industries, research domain, and environmental monitoring and human healthcare fields. Portable and wearable pressure sensors are fabricated as interlocked structures composed of composite polymers, such as poly dimethylsiloxane (PDMS), combined with conductive active nano materials, such as metals, carbon nanotubes, reduced graphene oxide (rGO), and graphene [2,3,4,5,6,7,8,12,13,14] These elastomer-based pressure sensors exhibit a high sensitivity, low detection limit, and rapid response, and can be utilized in piezoresistive electronic devices. According to the existing reports, the design of piezoresistive Si NR sensors is limited to the cantilever type, as it can efficiently detect the torque/force [26,27,28,29,34] Despite their superior mechanical and electrical properties, high-aspect-ratio Si NR arrays have not yet been applied in the design of pressure sensors that could be used in healthcare devices. To fabricate complementary metal–oxide–semiconductor (CMOS)-compatible air flow sensors, it is desirable to utilize the piezoresistive property of Si NRs to enable ultra-low-range pressure detection including that of air tur bulence, human breathing, and acoustic vibrations in air [30]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
