Compliant Electrodes

Early demonstrations of wearable devices have driven interest in flexible lithium-ion batteries. Previous demonstrations of flexible lithium-ion batteries trade off between low areal capacity, poor mechanical flexibility and/or high thickness of inactive components. Here, a reinforced electrode design is used to support the active layers of the battery and a freestanding carbon nanotube (CNT) layer is used as the current collector. The supported architecture helps to increase the areal capacity (mAh cm-2) of the battery and improve the tensile strength and mechanical flexibility of the electrodes. Batteries based on lithium cobalt oxide and lithium titanate oxide shows excellent electrochemical and mechanical performance. The battery has an areal capacity of ≈1 mAh cm-2 and a capacity retention of around 94% after cycling the battery for 450 cycles at a C/2 rate. The reinforced electrode has a tensile strength of ≈5.5–7.0 MPa and shows excellent capacity retention after repeatedly flexing to a bending radius ranging from 45 to 10 mm. The relationships between mechanical flexing, electrochemical performance, and mechanical integrity of the battery are studied using electrochemical cycling, electron microscopy, and electrochemical impedance spectroscopy (EIS).

Smart Fabrics or fabrics that have the characteristics of sensors are a wide and emerging field of study. This thesis summarizes an investigation into the development of fabric sensors for use in sensorized socks that can be used to gather real time information about the foot such as gait features. Conventional technologies usually provide 2D information about the foot. Sensorized socks are able to provide angular data in which foot angles are correlated to the output from the sensor enabling 3D monitoring of foot position. Current angle detection mechanisms are mainly heavy and cumbersome; the sensorized socks are not only portable but also non-invasive to the subject who wears them. The incorporation of wireless features into the sensorized socks enabled a remote monitoring of the foot.

Dielectric elastomers are a class of electro-active polymers (EAPs) which have been used for smart structures, such as muscle-like actuators. These materials with compliant electrodes are transducers of electrical to mechanical energy, with extremely large strain and good efficiency. A thorough understanding of the physics underlying the nature of different electrode materials can help modify actuator response. The objective of this paper is to investigate the effect of 4 different electrodes (graphite powder, carbon filled grease, silver filled grease and electrically conductive silicone rubber) on the performance of dielectric elastomer actuators. The principle of operation, the method of fabrication and test method of planar actuators are discussed. Effects of different driving voltages and different prestrain values on the actuator response have been studied. Electrical conductivity under strain, electrode surface uniformity and mechanical compatibility with substrate, as the mo...

This paper describes an ultra-compliant paryleneplatinum neural probe embedded in a biodissolvable delivery vehicle. High probe compliance is achieved using thin wires (width of 10.0 μm and thickness of 2.7 μm) and by meandering the probe. The insertion of the ultra-compliant probe is achieved by encasing it in a dissolvable delivery vehicle made from molded carboxymethylcellulose. In vivo implantations of delivery vehicles with 1.5 mm long shanks, widths of 100 μm and 300 μm and a targeted thickness of 135 μm have been done through the dura in the cortex of Sprague-Dawley rats at a speed of 80 mm-s -1 . The delivery vehicle becomes a gel over a period of less than three minutes, after which the handling portions of the delivery vehicle are removed leaving the shanks embedded in the brain.

Folding, conformable electronic devices cannot be realized
until fl exible batteries that match device form-factor and power
requirements are developed. Existing fl exible batteries exhibit a
severe limitation due to internal short circuits during flexing.
[1] In the present work, we demonstrate a printed alkaline battery fabricated with a polyacrylic acid (PAA)-based polymer gel electrolyte (PGE). The electroactive materials were embedded into a mesh structure providing highly fl exible electrodes. The fl exible alkaline battery showed an open circuit potential of 1.52 V and discharge capacity of 5.6 mAh cm − 2
when discharged at 0.5 mA.The discharge capacity of the printed battery was characterized in bend conditions ranging from 3.81 cm to 0.95 cm bending radii without any decrease in performance compared with the planar state. Two batteries connected in series and bent to a radius of 0.3 cm were able to power a green light-emitting diode (LED)

Dielectric elastomers are a class of electro-active polymers (EAPs) which have been used for smart structures, such as muscle-like actuators. These materials with compliant electrodes are transducers of electrical to mechanical energy, with extremely large strain and good efficiency. A thorough understanding of the physics underlying the nature of different electrode materials can help modify actuator response. The objective of this paper is to investigate the effect of 4 different electrodes (graphite powder, carbon filled grease, silver filled grease and electrically conductive silicone rubber) on the performance of dielectric elastomer actuators. The principle of operation, the method of fabrication and test method of planar actuators are discussed. Effects of different driving voltages and different prestrain values on the actuator response have been studied. Electrical conductivity under strain, electrode surface uniformity and mechanical compatibility with substrate, as the mo...