Postdoctoral Fellow | Harvard University Whitesides Research Group
Integrating Soft Sensor Systems Using Conductive Thread
(a) A single-core copper wire inserted into a microfluidic channel in an Ecoflex substrate. Due to the high-bending moment and rigidity of the wire, when the external part of the wire moves it causes movement inside the channel. This movement can lead to delamination and degradation of the device. (b) When conductive thread is inserted into a microfluidic channel in an Ecoflex substrate then external movement does not affect the position of the wire inside the channel. (c) Schematic showing a poor connection between the wire and the liquid metal. The copper wire has moved out of the bulk-liquid and only touches the semi-conducting gallium-oxide film. (d) Schematic showing a good connection between the liquid-metal and a wire. The wire is wetted by the eutectic, and makes an electrical connection to the conductive bulk-liquid.
Photographs showing the withdrawal of (a) conductive thread and (b) copper wire from a galinstan droplet. The galinstan wets more onto the conductive thread than the copper wire.
Top view of the integrated soft pressure sensing system. (a) Normal-force pressure sensor made with a Galinstan-filled microfluidic-channel encapsulated in an Ecoflex substrate. (b) Conductive thread is used as interconnection between the pressure sensor and the flexible PCB. The serpentine shape provides strain-relief. (c) A flexible PCB consisting of hard electronic components, including a bridge circuit, an amplifier, a microcontroller, and LEDs