We review products developed for all three form factors. All three product sectors present distinct communication challenges and (hence) potential communication value opportunities. On 14 March 2003 Hitachi announced a product called a Mu chip. It was very small (or else was photographed against a very big finger). This device is illustrated in Figure 19.1. Actually it was 0.3 millimetres square, half the size of the RF tags on the market at the time and was manufactured using a 0.18-micrometre process as opposed to the 0.35-micrometre process generally in use then. The chip operated at 2.4 GHz and stored a 128-bit ID and could be read from a foot away (30 cm). The antenna, which cannot have been very big, was attached to two electrodes at the top and bottom of the chip, which apparently was very clever. The Mu chip was intended as an alternative to bar codes or conventional RF tags for use in supply-chain management, product traceability and security and was packaged as a complete system including readers, software and networking infrastructure. RF tags at the time cost about 40 cents each. In practice, the device never achieved traction either in the business and asset tracking market or in the consumer space and the web site is now closed. Table 19.1 Microdevice form factors and functionality - three examples Small Very small Very very small Grain of Rice < 4 Grain of Sand <2 millimetres Grain of Dust <500 millimetres micrometres Example Product Memory Spots 1 Motes (Intel web site)2 Mu Chip³ (HP Labs) Hitachi Information delivery Information collection device Identification device device (RFID) 2 mm by 4 mm including 1 mm by 1 mm (mote sized) 0.4 mm by 0.4 mm by integrated antenna Typically with sensing capabilities - 60 micrometre 256 kilobit to temperature, light, vibration, 0.15 mm by 0.15 mm by 4 megabit storage acceleration, air pressure 7.5 micrometre Data transfer rate up to Data transfer rate Device and Data transfer rate 12.5 10 Mbits/s application dependent kbits/s Distance - close coupled Distance 