Is an e-book reader a suitable tool for carrying your research library with you? Like most scientists, I have a large collection of research papers (as PDF files) and want to have them with me, so that can read when I'm on the bus, in a café, waiting for a lecture to start, or in the evening in bed. At conferences or meetings, I often want to look up details or show a figure to a colleague. Here are my experiences using an e-book reader: in short, it didn't work. Instead, an inexpensive tablet computer is a better choice.

What a scientist needs

Before I detail my experiences, let me make clear that this is not a review of any particular e-book reader, and I'm not going to express an opinion on the advantages or disadvantages of e-books or printed books in general. I'm writing about the specific needs of researchers in the hope that it is helpful to other scientists who consider buying a reader. When I was shopping for one, I found plenty of reviews about the technical quality of different devices as well as the systems for buying and downloading e-books.

However, only few reviews mentioned the specific needs of researchers who work with PDFs from research journals rather than e-books. I have hundreds of papers, and I often read several at the same time to compare their findings. Even within each article, I rarely read them linearly from the beginning to the end like a novel, but have to jump backwards and forwards to compare text to figures or find some details that were mentioned earlier. I assume that many researchers will use the literature in a similar pattern.

I am not looking to replace my office computer. For studying important papers in detail and other serious literature work, it is still much more efficient to sit at a desk with a big screen, possibly with printouts of the papers, and the ability to take extensive notes both on computer and on paper. The mobile library, on the other hand, is most useful for background reading and for quickly looking up information when I'm out of the office.

Experiences

How useful was the reader for me, and what were the problems? For the record, I have an "iriver story" - it has a 6 inch touchscreen e-ink display and uses Adobe Digital Edition to display PDFs. However, my comments are very generic and should apply to most e-ink readers. Here are the issues:

• Finding/organising articles is difficult and tedious. You can group articles into folders, and you can search for phrases in the file name, but there is no fulltext search. Navigating between folders is awkward: the interface is not designed for large numbers of files (it shows only a few file names at a time), and due to the slow e-ink display, moving through a folder takes too long to be practical. When you have ten minutes on the bus, you don't want to spend five minutes finding and navigating to the article. Of course, once it's open, it will be there quickly next time, but it is still very impractical if you want to finish an article on the e-book reader that you had started on the office computer, or when you quickly need to check something in an article that you saved months ago.
• Only one article can be opened. You cannot easily switch between two or more files, whereas on a normal computer or tablet you can keep other files open in the background and switch between windows. Reading or comparing two or more articles is very complicated - each time you switch articles, you have to go to the main screen and navigate to the other one.
• Navigation within the article: You can search within an open article, so that's helpful. However, again due to the slow e-ink display, jumping backwards and forwards a few pages is very time-consuming. The interface is designed for linear reading, not for many page changes.
• Display size: E-ink is actually very readable and much more relaxing to the eyes than a computer or tablet screen. However, the 6 inch display is a bit on the small side, and there are no good zooming options in the software. Scientific papers usually don't come in special e-book formats, but as PDFs designed for printing on A4 paper. The e-book reader, when set to protrait mode, will display a full page on its display, and in landscape mode it displays half a page. Half a page on a 6-inch display is just about readable - adequate enough in a well-lit quiet environment, but on a moving bus it was often difficult to read. Although one can zoom into parts of the page, it is a lengthy process, and then you can't easily move around on the page while keeping the same zoom level. The software also allows you to "reflow" the text, i.e. forget the original page layout and show the text in standard sized letters without formating, so that it is easier to read. This works with some papers, but not with all, depending on how it was created by the publishers. Many papers will produce spurious line breaks that are distracting, and if the page layout contains figure captions or info boxes, the "reflowed" text can get messed up. Still, the display quality wasn't really my main problem, compared to the slow navigation.
• The display is black/white only, with limited grayscales. This can be an issues e.g. in geoscience, as many papers show geographical maps where the colour-coding contains the main information. However, personally I didn't find this much of a limit.
• Some other reviews have mentioned that some e-book readers offer features to annotate PDFs. My reader has some limited bookmarking features, but I don't generally use annotations on PDFs, so it's not a feature that would be important to me.

Therefore, in my experience, using an e-book reader for scientific papers was much more awkward and much less useful than I had hoped, and for several months I had the reader in my bag without ever using it. Again: this is the specific experience of trying to use it for my research library. I do see that an e-book reader can be great for reading linear books, whether fiction or non-fiction. Perhaps researchers with different habits or in different fields will also find e-book readers more useful. But for the way I use scientific papers, they are not the best choice.

A tablet as better alternative

As an alternative, I tried tablet computers - successfully. My first one was a no-name Android tablet that I got very cheap a few years ago, but now I've moved to an Arnova 8b G3, an Android tablet that one can get for less than €100. In summary: the no-name tablet is ok but limited, but the newer Arnova is perfect for my needs. Again I don't want to write reviews about the individual models, just summarize the experience for the specific use as a scientific library, and these comments should be valid for most tablet computers in the lower price range. If you want to buy one, it is advisable to consider what else you want to do with it - use it just as a basic reader, or as a full mobile office - and choose appropriately; there are numerous tech sites that will review individual models.

Both tablets have adequate software ("OfficeSuite") for reading PDFs, with all the zoom and page navigation options that one needs. The Android system also comes with a reasonable file manager, so all the navigation problems that I described above are no issues at all with the tablets. Also, one can install other file managers with more features or other programmes if needed. A big advantage is that Android comes with a (basic but adequate) internet browser (and you can install several others, including Opera and Firefox). If you use an internet service like CiteUlike to organise your references, you can access it directly to find the paper you're looking for, and then read the PDF that you saved earlier on the tablet's SD card.

The screen sizes (7 inch for the no-name, 8 inch for the Arnova) and resolution (800*600) are also perfectly adequate, and as you can zoom in and out easily, the size is much less an issue than it was for the e-book reader with its full or half page display. The brightness of the screens is high enough for most situations, except bright sunlight.

In other words, even basic tablets already have everything that's needed for a scientific library. I chose the Arnova not because it's special, but simply because I happened to find one at a good price. There are, however, a few practical things I would look out for when buying:

• Power adapter: Use a model that can be charged via USB cable. The no-name tablet needs a special 9V power adapter, and it's a hassle to carry that around. The Arnova has a standard micro-USB slot, the same as my mobile phone, so it can be charged with a small cable from any computer (or a small USB mains adapter).
• Battery life: Consult tech reviews before you buy a specific model. The no-name tablet had a rather weak battery and bad power management, so it worked for only 3-5 hours even in standby - I had to keep it switched off completely and accept a 2 minute bootup every time. The Arnova gives me about 3 or 4 hours reading time, but more importantly it lasts a few days on standby. It's usually enough to recharge it over night to be able to use it all day; and on intense days I can easily top it up at any computer or power socket (thanks to the USB cable). Of course, this is no match for the proper e-book reader which runs for weeks without recharging. However, in everyday life, the battery life isn't a problem.
• Capacitive screen: this touchscreen technology is more responsive than the resistive screen - the Arnova has a capacitive screen, the no-name has a resistive screen. The cheaper resistive screen can be quite sluggish - not a problem when you're just reading, but when you navigate in the file manager and scroll through lists, my no-name tablet often didn't react or it opened files that I hadn't intended to open, interrupting my work flow. The capacitive screen on the Arnova is responsive and easy to use.
• Although a bit beyond the scope of this article, it is worth mentioning that many tablets in the lower price range may have limitations one should be aware of. One issue is that they often can't use the Google Play market to install new applications. Personally I didn't find this problematic, as there are several other app markets (SlideMe, Androidpit etc.), but if you want to use the tablet with other apps, it's worth checking if you can get them. Also, my Arnova didn't include the calendar app, and apps don't have write access to an external SD card. Not a big deal for me, but if you need these functions, you should check before you buy.

When I got the Arnova, I had intended to use it mainly as a mobile PDF reader, but it now also acts as a RSS reader (very good for journal alerts!), a digital picture frame, an internet browser, a mailer and a few other things that are handy when I'm out. Nonetheless, it also serves its main purpose very well: to act as a very capable scientific library.