Wireless Movement & Sniffing Monitor

Using an XBee, Arduino, and some sensors (accelerometer, pressure sensor), we put together this wireless movement/sniffing monitor.  The device is powered by a 3.7V rechargeable Lithium Ion coin cell.  The small (4cm x 4cm) board connects via a magnet so it is easy to put on and off.  Optional LEDs can be used for tracking.  I am using the native ADCs on the XBee for passing signals.

In the next post I will put the Arduino code and circuit for receiving the signal from the sensor board.

The accelerometer is Analog Devices ADXL335: http://www.analog.com/static/imported-files/data_sheets/ADXL335.pdf
The amplifier for pressure sensor is Analog Devices AD627: http://www.analog.com/static/imported-files/data_sheets/AD627.pdf
The pressure sensor is Honeywell 24PCAFA6G: http://sccatalog.honeywell.com/pdbdownload/images/24pc.series.chart.5.pdf

The magnetic clip is made so as to connect the pressure sensor to a cannula on the other side of the connector and to prevent arbitrary rotation.

Here is a video of the magnetic clip:

Here are pictures of the device:

Front of board with XBee removed.  Pressure sensor and magnetic attachment on bottom.

Back of board has battery clip.

Front of board with XBee.

Magnetic attachment around pressure sensor and mating piece (right).

Here is the link to the project files and some additional information below:
https://docs.google.com/folder/d/0Byu6zHhzDPqVQlEtMFBaeHRZUlE/edit?usp=sharing

The PCB Layout that I used.

The circuit schematic.

Sniffs and Spikes

My next technical challenge in the lab is to set up simultaneous recording of sniffing and of neural spikes.  I am planning on putting together a compound device integrating a silicone probe for measuring neural activity and a pressure sensor for measuring sniffing simultaneously.  The trick will be to have all inputs and output go through a single tether wire.  Currently my thinking is that I can use a TDT ZIF-Clip with 64 channel capacity and use 32 of the channels for the electrodes and 4 channels for the pressure sensor (+V, -V, Gnd, Out).  For a commutator, I am thinking of getting a 36 channel slip ring system from the orbex group.

UPDATE:  Turns out there are issues with integrating other inputs/outputs into the ZIF-Clip from TDT.  Currently, the clip uses nearly all of its channels for electrode signals and it is difficult to break any channels out.  My alternate solution is to just put up with a second (third) wire to the head and continue attaching the sniff sensor via a magnet.  We are now miniaturizing our sniff sensor so that it may fit better on the head alongside the electrode and micro drive.