So to be a bit curious, I've never really heard of a camera sensor brush. The only thing I know to use to touch the sensor directly is a product like this:
Amazon.com: Digital Survival KIT - Sensor Swab Type 2 (w/Eclipse): Camera & Photo
It is a soft cloth on a plastic stick that is soaked in a alcohol solution to pick up dust and debris and other things off the sensor. Usually a brush such as:
Amazon.com: Nikon Lens Pen + Cameta Microfiber Cloth Cleaning Combo Kit for Digital SLR Cameras, Lenses, Camcorders, Binoculars & Scopes: NIKON: Electronics
Is more suited for brushing dust off lenses, not sensors. This is because generally these brushes leave particles behind and only pick up large stuff.
Now, you may try using the lens swab with solution to wipe the sensor, but the least destructive thing you can try now is a blower:
Amazon.com: Giottos AA1900 Rocket Air Blaster Large - Black: Electronics
I've almost always have been able to clean my sensor in my k-x with the rocket blower. I've only had one situation where I needed the sensor swab (something sticky got onto my sensor). If your brother in law has a blower like what I linked, you can try that - mirror lock up the camera, face it downwards, point the blower into the mirror cavity (carefully, do not touch the sensor), and squeeze very hard for several tries. The sheer air pressure blowing onto the sensor will most likely dislodge anything on the sensor, and will then fall downwards out of the camera.
Also - one thing to also try is the in-camera dust removal function. I'm not sure if you've used it already, but try it - and keep using it with the camera in different orientation (facing forward, down, upside down, right side, left side, etc). It might do enough.