Prototype

SEC DAQ

A 4-channel, 100 pF capacitance DAQ with active shielding designed for use with the Soft Elastomeric Capacitor (SEC) sensors but could be used for anything.

This data acquisition can measure SECs in the range of 15-115 pF, with an asynchronous sampling speed of 400 S/s on a single channel.

This hardware was used in various papers, including:

1. Downey, Austin, Anna Laura Pisello, Elena Fortunati, Claudia Fabiani, Francesca Luzi, Luigi Torre, Filippo Ubertini, and Simon Laflamme. "Durability and weatherability of a styrene-ethylene-butylene-styrene (SEBS) block copolymer-based sensing skin for civil infrastructure applications." Sensors and Actuators A: Physical 293 (2019): 269-280.
2. Downey, Austin, Mohammadkazem Sadoughi, Simon Laflamme, and Chao Hu. "Fusion of sensor geometry into additive strain fields measured with sensing skin." Smart Materials and Structures 27, no. 7 (2018): 075033.
3. Yan, Jin, Austin Downey, Alessandro Cancelli, Simon Laflamme, An Chen, Jian Li, and Filippo Ubertini. "Concrete crack detection and monitoring using a capacitive dense sensor array." Sensors 19, no. 8 (2019): 1843.

Hardware design notes

v0.9.0

1. Contains all the older files.
2. Contains the 2-board PCB design

v0.9.1

1. This is stable release.
2. A 4-channel SEC DAC with isolated signal

v0.9.2 (future version)

Improvements needed

High importance

1. The files needs to be cleaned up, and put back into a single KiCad file.
2. Compress the board layout so the DAQ sits inside the Arduino shield. (Reduces the wasted space)
3. Remove the ground tabs as adding a shield is a further work outside of these single box DAQs
4. Use a lower current draw opotcoupler, I think a CPC1301 should work.

Medium importance

1. Move trigger housing into the board so it does not hang over.
2. Change the surface mount D-sub to a edge mount D-sub with signal/shield on top and ground on bottom.
3. Add a switch for the time stamp so the DAQ only returns a time stamp if the switch in enabled. Will require a 14 pin IDC connector.

Low importance

1. Enlarge the CDC filter capacitor solder pads
2. Add LED to the trigger circuit to help with trouble shooting (check current draw problems)

Licensing and Citation

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Cite as:

@Misc{DowneySECDAQ,
author = {Austin Downey},
howpublished = {GitHub},
title = {{SEC} {DAQ} Open Source Hardware Design},
groups = {{ARTS-L}ab},
url = {https://github.com/ARTS-Laboratory/SEC-DAQ-Open-Source-Hardware-Design},
}