Handheld devices for caregivers have yet to find the sweet spot that will drive adoption. Part of the problem has been a lack of well designed applications that meet market requirements. The other part has been the devices themselves - either too big, too heavy, too expensive, and not enough battery life. Did I mention too expensive?

Here we have a trio of devices from Sony, Nokia and Aeronix. All three are Linux based devices with WiFi, web browser and a variety of chat messaging applications.

The Sony Mylo (pictured right) is the most attractive, is priced at an affordable $350, and sports an integrated keyboard.

On the upside, the device is expected to support VoIP and instant message services available from Google Talk, Skype, and Yahoo! Additionally, the Mylo will include nearly a gig of user file storage, expandable via Memory Stick, along with players for MP3s, ATRAC, WMA, and MP4 video.

The Mylo measures 1 x 4.8 by 2.5 inches, and sports a 2.4-inch QBVGA (320 x 240) LCD screen. It supports 802.11b networking, with WEP and WPA encryption. Text entry is done through a retractable thumb keyboard.

The Nokia 770 is also priced at $350 and has a touch screen user interface (no keyboard).

The Linux-powered Nokia 770 Internet Tablet offers convenient Internet browsing and email through built-in WiFi, or via a Bluetooth connection to a compatible mobile phone. The device boasts a 4.3-inch, 800 x 480 pixel touch-screen, plus integrated WiFi, Bluetooth, and a reduced-size MMC (RS-MMC) card slot.

Although positioned as an "Internet tablet," the 770 has much wider applicability. Bundled software currently includes: web browser, email client, Internet radio, news reader, media players, image viewer, file manager, search, calculator, world clock, PDF-viewer, notes, sketch, and games. Additionally, a broad and growing range of software can be downloaded and installed onto the device from the 770's community website.

My favorite is the Aeronix Zipit...

The Zipit is marketed under brand names that include ZipitWireless and K-Byte, and is currently available at Target and TigerDirect, priced at $99, in colors that include white, silver, blue, red, and pink. It includes an 802.11b WiFi radio, 16-color greyscale LCD with QVGA (320x240) resolution, and a thumb keyboard with rubber buttons. Also included is a stereo DAC (digital audio converter) connected to a speaker and headphone jack.

According to the AiboHack Project, a group of hackers devoted to Sony's robotic dog, the Zipit is based on a Cirrus EP7312-CR-90, an SoC (system-on-chip) with an ARM720T core that clocks up to 90MHz. This chip is supported by several Linux distributions, including FSMLabs's real-time RTLinux.

The Zipit boots from 2MB of Flash, reportedly, and has 16MB of SDRAM. David Anders is reportedly investigating a way to add an MMC memory card slot to the device, to expand its storage capacity, according to Tim Riker's Embedded Linux website, which hosts project pages devoted to the Zipit.

On the software side, the Zipit comes stock with a 2.4.21 Linux kernel with Russell King's ARM patches. The WiFi chip is powered by a patched version of Agere's Linux WiFi driver. Other open source software includes busybox, uClibc, glibc, and wireless tools. Proprietary software includes the bootloader, audio driver, and the monolithic native ARM application that provides the device's user interface and all its features, according to Aeronix's Zipit Linux page.

Writing software clients for hand held devices is not a trivial undertaking, and these devices are no exception. What's intriguing is the idea of using devices like these for wireless VoIP clients (a la Vocera) and alarm notification from patient monitors and IV pumps and other medical devices. These devices are small and light weight, have graphic displays (for sample arrhythmia waveforms), and keyboards (okay, the Nokia has a touch screen keyboard). Compared to a $2,000+ ruggedized PDA from Symbol or Hand Held Products these devices are a steal.