Form factors

Commercially available consumer electronic devices such as cell phones can be useful in disasters. A smartphone (e.g., Apple iPhone, Samsung Galaxy S4, Blackberry) with cellular data or Wi-Fi connectivity combined with a camera can be a powerful solution that is inexpensive, readily available, and allows disaster workers to “bring your own device.” Their small size makes them easy to carry and be easily available. However, the screen size of most smartphones is relatively small, making it difficult to visualize large amounts of data on-screen at once. This can limit the amount of information that disaster workers can process at one time and makes data entry more cumbersome, particularly for those wearing personal protective equipment.

Tablet computers (e.g., Apple iPad, Samsung Galaxy Tab, Microsoft Surface) solve the issue of small screen size and often offer longer battery life; the tradeoff however is decreased portability and increased difficulty in handling. These problems are not inconsequential, as disaster workers in the field often require both hands to accomplish many tasks and may find limited options for storing their device while maneuvering among patients and providing care. Whereas a smartphone can be dropped into a pocket, tablet computers are harder to carry and more likely to be dropped and/or misplaced. Most consumer electronic devices are not designed for the types of physical challenges that can be found during a mass casualty incident (MCI), including shock, vibration, dust, humidity, water, chemical exposure, and extremes of temperature. Rugged cases are available that meet standards (such as MIL-STD-810G) for imperviousness to such threats. These cases can be cumbersome and add additional weight; these problems must be balanced against the extreme difficulty of repairing or replacing broken components in austere conditions.

A novel class of wearable technologies (e.g., Google Glass, Sony SmartEyeglass) may provide a compromise as they provide many of the functions of a smartphone and can be worn, allowing the user full use of their hands. This form factor has unique features that have tremendous potential for emergency field use. The device can stream live video from the user’s point of view so that incident commanders can quickly gain situational awareness in advance of arriving on the scene. The screen is located in the user’s peripheral visual field and can provide critical scene safety information or detailed information on the location and conditions of victims in need of rescue. This class of device has tremendous potential, but is currently hampered by limited battery life and heavy dependence on networked resources.

Thin versus thick client

When choosing or designing an application for field use, one of the most important initial decisions is whether to use a so-called thin client or a thick client model. Thin client devices relegate the bulk of data processing to a centralized server, using the local device primarily to display information to the user. This is contrasted with thick client devices, which process the data locally on the user’s device. The difference is not always completely dichotomous, and it is possible to have an application that draws on the features and benefits of both models.

Each approach has its advantages and disadvantages. Thin client applications typically allow the user to view the output of a program that is running on a remote computer, using communication networks to present the information. This approach requires less powerful hardware and can result in smaller form factors, inexpensive devices, decreased power consumption, and longer battery life. In such models, most logic and data processing occurs on the server, which greatly simplifies maintenance and software updates. One update on the server can instantly improve the functionality for large numbers of users. This type of rapid iterative development can be essential in disasters, as application requirements can change quickly as the situation unfolds and details emerge. Changes can be made both quickly and frequently without having to update individual devices or adding tasks to responders who may already be maximally extended. Most modern web applications are built using the thin client model, resulting in a large reservoir of talent from the web-based software community. However, thin client models are highly dependent on reliable and fast communication channels, most commonly Wi-Fi, cellular data (i.e., 3G, 4G, LTE), or satellite communications. Interruptions in this connectivity (such as damage to cellular infrastructure) can lead to near complete loss of functionality.

Thick client models are more immune to disruptions of infrastructure and can utilize slower and less reliable methods of communication. They do not rely upon a central server for basic functionality and can allow users to continue working, viewing, and entering data while the device is not connected. When connectivity resumes, these systems can upload any data entered and download available updates. Less dependence on communication channels can be advantageous as these networks are doubly threatened. Direct impact from the event often damages the underlying infrastructure; also, the demand on the communication networks increases sharply as the general population engages in health and welfare checks on friends and family in the aftermath. This independence, however, comes at a cost. Devices for thick client models often need more storage, memory, and computing power, which can increase cost and weight and consume more power. Also, data that sit unsynchronized between servers and devices quickly become stale and less actionable. Software on these devices must be updated often, and more effort is required to maintain the devices and address disparate versions that users might be running.

There is no solution that is ideal for all situations. The correct choice depends on the unique characteristics of the scene and the availability of connectivity and can rapidly change as things progress.