Piezoresistive response of nano-architectured Ti x Cu y thin films for sensor applications

Abstract

The present work reports on the development of piezoresistive Ti x Cu y thin films, deposited on polymeric substrates (PET). The general idea was to analyse the influence of the Cu concentration on the signal response of the Ti-based transducers, exploring the possibility to use this thin film system as force and deformation sensors in biomedical sensing devices. The GLancing Angle Deposition, GLAD, technique was used to change the typical normal columnar growth microstructure into inclined (zigzag-like) architectures, aiming to tune the mechanical and electrical responses of the thin films, which may offer unique opportunities for several sensing devices. Inclined (zigzag grown) thin films were prepared with increasing amounts of Cu and characterized in terms of the most relevant properties for sensing applications. The piezoresistive response was analyzed trough the evaluation of the Gauge Factor, K. The incident angles of the particle flux  = 45º were used to prepare the nano-architectured zigzag Ti x Cu y thin films. The Gauge factor ranges from 1.24 ± 0.03 to 16.34±0.43 for intermetallic Ti 0.92 Cu 0.08 and pure Cu thin films, respectively. For the deposited thin films small voids are formed and the voids density decreases considerably with increasing Cu content. Taking in account the: electrical resistance linearity, low noise and the highest K value found for Ti x Cu y films (K= 3.6±0.1), the most promising results were obtained when the polymer was coated with a stoichiometry ofTi 0.37 Cu 0.63. The overall set of results also show the viability of these materials to be used as piezoresistive sensors, namely in biological environments, such as catheters, needles or endoscopes with sensing capabilities.

Fabrication, Characterization and Implementation of Thermo Resistive TiCu(N,O) Thin Films in a Polymer Injection Mold

“…Titanium-copper (TiCu) thin films with a concentration of roughly Ti 50 Cu 50 at % were DC sputtered from a bulk titanium target (with size of 200 mm length, 100 mm width and 6 mm thickness, and 99.96 at % purity), and placed at 70 mm from the substrate using a customized vacuum chamber. Taking into account previous results [16], the Ti target was adapted with constant amounts of Cu pellets (with specific area of~0.2 cm 2 ), symmetrically distributed along the preferential erosion area (~50 cm 2 ) [17], as seen in Figure 1a, with the purpose to tune the Cu content in the thin films to around 50 at %, as described in [18].…”

CuTi Nanotellerinin Germe Oranı ve Boyuta Bağlı Mekanik Davranışı

“…Semboshi ve Takasugi [18] hidrojen atmosferinde yaşlandırılarak yüksek mukavemetli ve yüksek iletkenliğe sahip CuTi alaşımlı bir tel modeli sunmuşlardır. Dahası, sensör uygulamaları için nano mimarili Ti x Cu y ince filmlerin piezo dirençli yanıtı [24], katmanlı Ti / Cu / Ti kaplı malzemelerin mekanik tepkisi ve kırılmasında intermetalik bileşenlerin gelişimi [25] ve hızlı katılaşma sırasında sıvı metalik Ti 62 Cu 38 alaşımının yapı oluşumu üzerindeki yüksek basıncın etkileri ile ilgili çalışmalar gerçekleştirilmiştir [26]. Yukarıda bahsedilen çalışmaların ekseni CuTi sistemlerinin atomik yapısı, cam oluşumu ve kristalizasyon süreçleri üzerine yoğunlaşmışken mevcut bilgi ve literatür araştırmalarımız CuTi nanotellerinin germe altında mekanik özellikleri üzerine herhangi bir araştırmanın yapılmadığı yönündedir.…”

Intrathecal Therapeutics: Device Design, Access Methods, and Complication Mitigation

“…In terms of intrathecal catheters, Saulino et al have already taken steps in that direction by exploring the incorporation of a pressure sensor into an ITB catheter as a means of detecting variations in CSF pressure that might indicate catheter malfunction. Other examples might include devices with on‐board miniature strain gauges to detect anomalous stiffening of the catheter that might be indicative of incipient granuloma formation, optical fiber sensors for real‐time flow cytometry during delivery of cell suspensions , and oxygen saturation sensors to alert the onset of respiratory failure in the event of malfunctions or delayed pump refill during intrathecal opiod delivery . Lastly, spinal cord stimulators are now integrating real‐time data from on‐board inertial accelerometers to optimize stimulation patterns and intensities in response to the patient's posture and activity.…”