Well a year on from the article the mass-production situation seems to be improving. Goodyear last month revealed a patent where a foam is incorporated in the tire production process which can be used as a pouch for a sensor.

Coincidentally Bridgestone followed with a concept, and Honeywell filed two more patents dealing with production TPMS SAW sensors incorporating the RFID tag.

Whereas TPMS would seem to have been the certainty for mass production wireless SAW use Schott have announced the production ready wireless SAW based torque sensor for automotive use.

For those who would like it here is an extract from the patent:

[0074]The invention provides for a small size strain sensor which has low sensitivity to magnetic fields furthermore it provide[sic] for an extraordinary precision of measurements of static and dynamic loads.

"16. Use of a strain sensor system,according to claim 15 for one or more of the following uses:
- as a torque splitter sensor
- as a torque sensor for electric power assisted steering (EPAS)
- as a crankshaft or flexplate torque sensor
- as a transmission output torque sensor
- as a drive shaft torque sensor
- as a shear strain sensor for a range of engineering structural applications
- as a tension-compression plus Poisson's ratio strain sensor for a range of engineering structural applications."

Both uses would appear to offer fuel saving potential - and with TPMS possibly hundreds of million batteries not ending up as waste.

Pirelli apparently are going to launch a piezo based TPM system later this year so even more chance of escaping from a battery based system.