Wrist phones and super batteries
Mobile phone technology continues to get smaller and more powerful
The present generation of cops probably knows that Dick Tracy is a fictional detective, but maybe not so much about his most famous gadget, the two-way wrist radio. Tracy wore a communicator on his wrist at a time when some police cars didn’t have radios, and the radio was eventually upgraded to a two-way wrist TV. Today’s Tracy has a two-way wrist computer. That doesn’t sound so far-fetched, now that we have devices which simultaneously serve as phones, televisions, computers, still-frame and movie cameras, gaming platforms, and music players — all in a box smaller than a pack of playing cards — but we’ve still not been given a true wrist radio.
A device introduced at the Consumer Electronics Show in Las Vegas earlier this month could change that.
The line of watch phones from Burg, available in the U.S. by April, incorporates a hands-free cellular telephone into a wristwatch. One model has just telephone and timekeeping functions, while another model lists Smartphone functions like an MP3 player, FM radio, and two-megapixel camera. The Burg website is not long on details at this writing, so it’s unclear whether the phone functions will require a Bluetooth headset or what sort of battery life one could expect. The line isn’t meant to replace a cellular phone so much as substitute for one in a pinch. By taking the SIM card from your GSM cell phone and inserting it in the Burg watch-phone, you could maintain cell contact during a run or a golf game. If these are going to be GSM phones, then they’ll work on the AT&T or T-Mobile networks, but not on Sprint or Verizon.
One Vital Issue: Battery Life
Battery life is likely to be the limiting factor with a phone this small. The consumer electronics industry has managed to pack an incredible array of devices into increasingly smaller packages, but battery technology hasn’t been as successful with miniaturization. The battery pack in my iPhone accounts for about 1/3 the bulk of the phone and half the weight, and the battery life of an iPhone is nothing to brag about. Take the battery out of your cell phone and it will probably weigh less than half as much; the same is likely true of your portable two-way radio.
Batteries also wear out far more quickly than the devices they power. A lithium ion (Li-Ion) battery will typically last for 300-500 charge-discharge cycles, gradually losing capacity and delivering fewer watt-hours as it ages. Research at Northwestern University is looking to produce a Li-Ion battery that will charge ten-times faster, and capable of delivering ten times as many watt-hours per unit weight. When a Li-Ion battery recharges, lithium ions pass from the cathode to the anode through an electrolyte sandwiched between thin sheets of graphene.
The migration takes place only at the edges of the graphene sheets, and there is just so much edge material available. The new process punches holes in the graphene, producing more edges for ions. The greater holding capacity comes from substituting silicon for carbon between the graphene sheets. In a carbon environment, it takes six atoms of carbon to accommodate one atom of lithium. If silicon is used, the ratio changes to four to one.
There is also some work being done with copper hexacyanoferrate electrodes that could extend a battery’s life to 40,000 charge-discharge cycles, so that the battery might just outlast the device it powers. Unfortunately, anything workable from either of these research paths is likely to take three years or more to bear fruit, so don’t sell your Duracell stock just yet.
In the meantime, take a moment to appreciate the incredible technology we have at our fingertips. Last week, I was watching the film Super-8, which is set in Ohio in 1979. The deputy sheriff in the movie uses a portable radio half the size of a cinder block, and I remember them being about as heavy. We’ve come a long way since then, and the ride is hardly over.