Novel silicone-based capacitive pressure sensors with high sensitivity for biomedical applications

Abstract

In this work, an investigation of the pressure-sensing properties of a silicone rubber was conducted. Small amounts of carbon black were added to the silicone during fabrication and the effect on the sensitivity was explored. A full investigation of the mechanical and electrical properties of each composition shows that adding carbon black to the material greatly increases its sensitivity to pressure. This increase in sensitivity appears to be related to improvements in the material’s permittivity, which increases with carbon loading.

Tactile Devices To Sense Touch on a Par with a Human Finger

“…In a typical tactile device an array of such capacitor elements (or pixels) are fabricated by using micro‐electromechanical systems57–60 (MEMS) technology 61. 62 The top electrode, where the contact pressure is applied, is deposited on a flexible filler (Figure 7 a) and, therefore, it is mobile in the verical direction with respect to the fixed, bottom electrode 63–66. The contact pressure causes a change in thickness Δ D = FD / AE , where F is the applied compressive force on the pixel, namely, the top electrode surface, and E is the compressive modulus of the flexible filler.…”

“…A typical tactile sensor element or pixel has the same construction as the capacitance‐based system (Figure 6), where the dielectric material is a piezoelectric film of thickness D and area A . The film deforms by Δ D on touching with contact force F to generate charges + Q and − Q at the two electrodes 63. 94–96 As the element is also a capacitor, the induced charge leads to a potential V across the pixel, as given by Equation (5), where d is the piezoelectric constant of the material.…”

Tastsysteme mit künstlichem Tastsinn wie beim menschlichen Finger

“…Eine Anordnung derartiger Kondensatorelemente (oder Pixel) in einem typischen Tastsystem wird mithilfe von Techniken zur Konstruktion mikroelektromechanischer Systeme (microelectromechanical systems,57–60 MEMS) hergestellt 61. 62 Die obere Elektrode, auf die der Kontaktdruck ausgeübt wird, befindet sich auf einer flexiblen Füllschicht (Abbildung 7 a) und ist daher relativ zur fixierten unteren Elektrode beweglich 63–66. Der Kontaktdruck ändert die Schichtdicke um den Betrag Δ D = FD / AE , wobei F die auf das Pixel, d. h. auf die obere Elektrodenoberfläche, wirkende Kraft und E der Kompressionsmodul der flexiblen Füllschicht ist.…”

“…Ein typisches Element oder Pixel eines Tastsensors hat den gleichen Aufbau wie bei den Kondensator‐basierten Systemen (Abbildung 6), wobei das Dielektrikum ein piezoelektrischer Film mit der Dicke D und der Fläche A ist. Bei einer Berührung führt die Kontaktkraft F zu einer Änderung der Filmdicke um den Betrag Δ D , und an den beiden Elektroden werden die Ladungen + Q und − Q erzeugt 63. 94–96 Da das Element auch ein Kondensator ist, führt die induzierte Ladung zu einem Potential U über das Pixel, das durch Gleichung (5) gegeben ist, wobei d die piezoelektrische Konstante des Materials bezeichnet.…”

Investigation into the pressure sensing properties of PVDF and PVB thick film capacitors

“…The most significant advantages to this approach are the rugged nature of the thick films and the flexibility that the process allows in terms of the choice of material. A wide range of oxides and polymers can be combined to produce devices with the required physical and chemical properties [9]. Finally, the devices can be fabricated without any moving parts removing some of the complex issues associated with MEMS sensors.…”