Low-cost polymeric microcantilever sensor with titanium as piezoresistive material

Shokuhfar, Ali; Heydari, Payam; Aliahmadi, Majidreza; Mohtashamifar, Mansour; Zahedinejad, Mohammad

doi:10.1016/j.mee.2012.07.067

Cited by 13 publications

(8 citation statements)

References 19 publications

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“…Under stress, unlike semiconductor piezoresistors in which deformation of energy bands results in change in electrical resistivity, in metal piezoresistors geometrical variations (strain) cause the resistance to change. Over the years, various metals and their alloys have been investigated for application in strain sensing which includes titanium (Ti) [ 231 ], gold (Au) [ 235 ], copper (Cu) [ 236 ], bismuth–antimony (Bi–Sb) [ 237 ], copper–nickel (Cu–Ni) constantan alloy [ 238 ], nickel–chromium (Ni–Cr) [ 239 ], palladium–chromium (Pd–Cr) [ 240 ], platinum (Pt) [ 241 ], manganese (Mn) [ 242 ], and nickel–silver (Ni–Ag) [ 243 ].…”

Section: Su-8 Polymer-based Piezoresistive Cantilever Sensorsmentioning

confidence: 99%

“…Designs such as the sensor reported in Ref. [ 231 ], where researchers have implemented titanium metal piezoresistor that does not require any adhesive layer.…”

Section: Su-8 Polymer-based Piezoresistive Cantilever Sensorsmentioning

confidence: 99%

“…More specifics of fabrication sequences and process parameters for realizing metal piezoresistor SU-8 sensors are detailed in Ref. [ 87 , 231 ], whereas doped polysilicon and CB SU-8-based cantilever sensors are reported in Ref. [ 230 , 260 ] and [ 217 , 218 , 233 ], respectively.…”

Section: Fabrication Details Of Piezoresistive Su-8 Polymeric Cantilementioning

confidence: 99%

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A Review on Surface Stress-Based Miniaturized Piezoresistive SU-8 Polymeric Cantilever Sensors

Mathew

Sankar

2018

Nano-Micro Lett.

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In the last decade, microelectromechanical systems (MEMS) SU-8 polymeric cantilevers with piezoresistive readout combined with the advances in molecular recognition techniques have found versatile applications, especially in the field of chemical and biological sensing. Compared to conventional solid-state semiconductor-based piezoresistive cantilever sensors, SU-8 polymeric cantilevers have advantages in terms of better sensitivity along with reduced material and fabrication cost. In recent times, numerous researchers have investigated their potential as a sensing platform due to high performance-to-cost ratio of SU-8 polymer-based cantilever sensors. In this article, we critically review the design, fabrication, and performance aspects of surface stress-based piezoresistive SU-8 polymeric cantilever sensors. The evolution of surface stress-based piezoresistive cantilever sensors from solid-state semiconductor materials to polymers, especially SU-8 polymer, is discussed in detail. Theoretical principles of surface stress generation and their application in cantilever sensing technology are also devised. Variants of SU-8 polymeric cantilevers with different composition of materials in cantilever stacks are explained. Furthermore, the interdependence of the material selection, geometrical design parameters, and fabrication process of piezoresistive SU-8 polymeric cantilever sensors and their cumulative impact on the sensor response are also explained in detail. In addition to the design-, fabrication-, and performance-related factors, this article also describes various challenges in engineering SU-8 polymeric cantilevers as a universal sensing platform such as temperature and moisture vulnerability. This review article would serve as a guideline for researchers to understand specifics and functionality of surface stress-based piezoresistive SU-8 cantilever sensors.

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Section: Su-8 Polymer-based Piezoresistive Cantilever Sensorsmentioning

confidence: 99%

“…Designs such as the sensor reported in Ref. [ 231 ], where researchers have implemented titanium metal piezoresistor that does not require any adhesive layer.…”

Section: Su-8 Polymer-based Piezoresistive Cantilever Sensorsmentioning

confidence: 99%

See 1 more Smart Citation

A Review on Surface Stress-Based Miniaturized Piezoresistive SU-8 Polymeric Cantilever Sensors

Mathew

Sankar

2018

Nano-Micro Lett.

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“…For the samples prepared with gold films and concentrations above 3 wt.% CNT, the geometric factor is the dominant one, but just below 2 wt.% CNT loading, the intrinsic contribution to the GF is dominant. In the case of the Ti-Ag films, the change in conductivity induces strong variation of the response of the sensors due to their varying electrical response, which superimposes the variation of the piezoresistive composite [21,38]. It can be further stated that whereas the electromechanical signal is mainly due to the polymer sensing A c c e p t e d M a n u s c r i p t 17 element for electrodes prepared with α = 60º and 80º, the strong variations in resistivity under mechanical solicitation for the sample prepared with α = 40º is ascribed to variation in the electrode itself.…”

Section: Page 16 Of 23mentioning

confidence: 99%

Nanostructured functional Ti–Ag electrodes for large deformation sensor applications

Ferreira

Lopes

Martin

et al. 2014

Sensors and Actuators A: Physical

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This paper reports on the development of thin film-based stretchable electrodes, suitable for different types of sensors. Columnar Ti-Ag thin films with a Ag content of 8 at.% were prepared by D.C. magnetron sputtering on carbon nanotube/poly(vinylidene fluoride) CNT/PVDF piezoresistive composites. GLancing Angle Deposition, GLAD, technique was used to change the typical normal columnar growth microstructure obtained by conventional sputtering, into different growing architectures, such as inclined columns and zigzag profiles, in order to tune mechanical and electrical responses of the materials. Three different incident angles of the particle flux, α = 40º, 60º and 80º, were used to deposit Ti-Ag thin films with the different architectures. Upon uniaxial stretching of the prepared zigzag thin films, the resistance of the thin film starts increasing smoothly for strains up to 3%. Above 10% strain, a sharp increase of the electrical resistance is observed due to film mechanical failure and therefore interruption of the electrical conductivity pathways. Furthermore, the influence of the thin film architecture was also studied with respect to the performance of piezoresistive sensors based on carbon nanotube/poly(vinylidene fluoride), CNT/PVDF, composites in which Ti-Ag coated films served as electrodes for signal acquisition. Electromechanical tests were thus performed in composites with CNT contents close to the percolation threshold, where the electromechanical response, characterized by the Gauge Factor, is the largest. The stability of the piezoresistive response was analyzed for the various architectures of the GLAD sputtered Ti-Ag electrodes, including incident angle and number of zigzag periods. It is shown that thin film architecture has a pronounced influence in the overall sensor response, A c c e p t e d M a n u s c r i p t 2 where the best results are obtained for piezoresistive polymer composites coated with Ti-Ag films, produced with intermediate (α = 60º) incident angles.

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“…High performance cantilever sensors have been realized with different class of materials like semiconductor [16][17][18][19][20][21][22][23], polymer/plastic [24][25][26][27][28][29], ceramic [30], etc. However, silicon remains at the core as the principle material due to its excellent mechanical and electrical properties along with its long term stability.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on the influence of buried oxide layer of SOI wafers on the terminal characteristics of a micro/nano cantilever biosensor with an integrated piezoresistor

Mathew

Sankar

2016

Biomed. Phys. Eng. Express

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Piezoresistive micro/nano cantilever sensors have been extensively utilized in the detection and quantification of miniscule forces generated due to the physical interaction of biomolecules. Due to the ultra-sensitive nature of piezoresistive cantilever sensors, they have found numerous applications, especially in the development of point-of-care testing systems for healthcare applications. Over the years, silicon-on-insulator (SOI) wafers have been widely utilized to realize silicon based piezoresistive cantilever sensors due to their performance and fabrication related advantages. Treatise encompasses examples where researchers have retained the buried oxide (BOX) layer of SOI wafers to realize piezoresistive cantilever devices. In this paper, we investigate the impact of BOX layer of SOI wafers on the performance of composite piezoresistive cantilever biosensors. Typically, the response of piezoresistive cantilever sensors is evaluated by considering only the electro-mechanical response. However, the design of such sensors is a multi-variant problem due to (i) their composite structure and (ii) interdependent nature of the electrical, mechanical and thermal characteristics. Therefore, in the present study, we devise a new figure of merit (FoM) defined as the product of sensitivity ratio and the square of resonant frequency of the sensor. The sensitivity ratio represents the ratio of the electrical sensitivity due to surface stress and thermal sensitivity of the sensor. The proposed FoM takes into account the interplay between the electrical, mechanical and thermal response of the sensor. Finite element method based numerical simulations are performed to model and investigate the influence of BOX layer on the thermo-electro-mechanical response of a square shaped silicon piezoresistive cantilever sensor. Simulation results show that the presence of the supporting BOX layer enhances the mechanical stability i.e. spring constant and resonant frequency of the sensor. In addition, it is found that the BOX layer reduces the zero bias deflection of the cantilever due to difference in TCE of the constituent layer materials. Furthermore, it is shown that by dimensional optimization of the thicknesses of the constituent layers, sensitivity ratio of the sensor with BOX layer can be improved up to 2.96.

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Low-cost polymeric microcantilever sensor with titanium as piezoresistive material

Cited by 13 publications

References 19 publications

A Review on Surface Stress-Based Miniaturized Piezoresistive SU-8 Polymeric Cantilever Sensors

A Review on Surface Stress-Based Miniaturized Piezoresistive SU-8 Polymeric Cantilever Sensors

Nanostructured functional Ti–Ag electrodes for large deformation sensor applications

Numerical study on the influence of buried oxide layer of SOI wafers on the terminal characteristics of a micro/nano cantilever biosensor with an integrated piezoresistor

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