Cloud-based computing infrastructure with enormous storage capability, coupled with new tools for remotely accessing, analysing and visualising data, is developing at an exponential rate in terms of the variety and scale of available information. The ‘sensor web’ is an area of particular interest, with many major industries increasingly looking at ways to apply sensor network technologies to develop new products and services. However, the practical realisation of sensor networks requires a scalable model, in which the basic building block, the sensor (or sensing platform) is very low cost to buy, requires little or no maintenance, and has a very long lifetime (Years). Understandably, attention has therefore focused on sensors that meet these requirements, like thermistors, photodiodes, and vibration sensors. However, despite the obvious tremendous value of integrating chemical sensing capabilities for distributed real-time environmental sensing, there are no existing examples of large-scale deployments. There are a number of reasons why this is so. Perhaps most importantly, biofouling and other issues cause changes in sensor response characteristics, which in turn requires regular calibration. Conventional approaches to liquid handling in these platforms drives up the price and complexity, and requires larger form factors for reagent and waste storage. The integration of new concepts for liquid control using fully integrated photo-actuated polymer valves offers a way forward, if issues related to reliability and response characteristics can be solved. These circulation systems are more biomimetic in nature than traditional microfluidic platforms based on silicon micromachining. In this paper, I will review the current status of environmental sensor networks, and present recent results based on photo-switchable gels and microvehicles that suggest we are moving closer to the realisation of efficient yet sophisticated microfluidic platforms that could provide the basis for future low-cost autonomous chemo/bio-sensing technologies.