nd T Mobility US press release, Summer 2011. Wireless User Hardware constructively interfere, while others will destructively interfere. Colour displays are realised spatially ordering IMOD¹6 elements reflecting in the red, green and blue wavelengths. Given that these wavelengths are between 380 and 780 nanometres the membrane only has to move a few hundred nanometres to switch between two colours SO the switching can be of the order of tens of microseconds. This supports a video rate capable display without motion-blur effects. As with the electrophoretic display if the image is unchanged the power usage is near zero. 5.2.6 Batteries (Again) - Impact of Nanoscale Structures One of the constraints in the design of portable systems is the run time between recharging. Battery drain is a function of all or certainly most of the components and functions covered in this chapter. Batteries are a significant fraction of the size and weight of most portable devices. The improvement in battery technology over the last 30 years has been modest, with the capacity (Watt-hours kg) for the most advanced cells increasing only by a factor of five or six, to the present value of 190 Wh/kg for lithium-ion. Other performance metrics include capacity by volume, the speed of charge and discharge and how many duty cycles a battery can support before failing to hold a charge or failure to recharge or failure to discharge. Self-discharge rates also vary depending on the choice of anode and cathode materials and electrolyte mix. For example, lithium-ion batteries using a liquid electrolyte have a high energy density but a relatively high self-discharge rate, about 8% per month. Lithium polymer self discharge at about 20% per month. As stated in Chapter 3 high-capacity batteries can have high internal resistance, which means they can be reluctant to release energy quickly. Lead acid batteries for example can deliver high current on demand, as you will have noticed if you have ever accidentally earthed a jump lead. Using alternative batter