The idea for the Touch Mouse came from a brainstorming session with my frequent collaborators at Microsoft Research Cambridge.
Nic Villars showed us a mouse that he had broken into parts and refactored so that the optical motion sensor was placed in a small movable 'island' underneath the index finger, connected via a flexible wire to central form which supported the palm. We soon realized that sensors could be placed under each finger, creating a new kind of multi-touch device. This was followed quickly by the realization that all kinds of multi-touch pointing devices were possible.
We were excited about combining these modalities; the mouse remains unequaled in tasks requiring precise positional control and multi-touch enabled us to expand the expressive range of the mouse through touch and gesture.
We developed five very different multitouch mice in order to explore the design space. This work was described in "Mouse 2.0: Multi-touch Meets the Mouse" (pdf link) and won the ACM UIST 2009 Best Paper Award.
While this broad investigation was useful as a research method, it was clear to me from early on that the capacitive touch mouse that Jonathan Westhues and I had developed was the best basis for a commercial product. While the functional prototype was completed in a matter of weeks, it took a year of advocacy before a product effort was launched.
I led the project through it's initial phases where we defined functionality, design, and addressed the key technical and manufacturing challenges. The product was released in Sept. 2010.