Paper-based "Zero-Cost" Printed Electroionic Gas Sensors

英国每年扔掉420万吨食物（价值125亿英镑），这些食物在其他情况下是安全的。目前，除了包装上的估计“使用”日期外，没有任何方法可以有效地确定包装食品，特别是新鲜食品，是否可以安全食用。然而，大多数食物在超过保质期后的一段时间内都是可以食用的。鉴于英国50%的粮食来自国外，减少粮食浪费和更有效地管理资源是减少对增加进口的依赖的重要步骤。此外，尽管使用保守的使用日期，但仅在英国每年仍有100万例食物中毒病例（20，000例住院，500例死亡，15亿英镑）由于变质的食物。用于监测腐败的低成本技术可以在减少浪费量和预防食源性疾病方面发挥重要作用。在这个为期12个月的项目中，将开发一种全新的基于纤维素纸的超低成本印刷电气气体传感器。这种新的多功能传感器技术利用了纸张的固有特性，在室温下工作，功耗低（微瓦级），一次性使用，重量轻，与当前的大批量打印技术兼容。我们的实验室原型制造用于产生该资助申请的初步数据，每个传感器的成本为0.005英镑，但通过大批量制造，成本可能会降低到0.0001英镑以下，使所提出的技术接近“零成本”。在这个价位上，这些传感器可以放置在每个食品包装中，从而可以监测食品的腐败程度。这将反过来防止食品的不及时处理，同时通知消费者变质的物品。（例如金属氧化物半导体-即MOS -或有机半导体），这项新技术利用了气体对水表面束缚层中离子浓度的影响（从空气中的水分吸附）存在于纤维素纤维上，因此术语电离子气体传感。与用于感测气体的其他技术不同，所提出的技术特别适合于在具有高相对湿度的环境中操作，已知这会降低现有技术的感测性能或寿命（例如，MOS）。我们的初步结果表明，这种新的传感器技术能够在低于4 ppm（本项目确定的检测限）的浓度下检测NH3（肉类等富含蛋白质的食品分解的重要副产品）-在监测腐败的相关范围内。该项目的最终成果是一种优雅而简单的一次性纸基印刷电离子气体传感器（PES），能够检测食品腐败，主要针对生肉。在未来，我们的愿景是将这项技术扩展到与RFID标签的接口，用于家庭，商店和食品加工设施的无线腐败监测。

The UK throws away 4.2 million tonnes of food each year (worth 12.5 billion GBP) which is otherwise safe to consume. Currently, there is no method to effectively determine whether or not packaged food items, especially fresh foods, are safe to consume other than the estimated "use-by" date on the packaging. Most foods, however, are good for consumption for an extended period past their use-by date. Given the fact that the UK sources 50% of its food from abroad, reducing food waste and managing resources more efficiently are important steps in reducing reliance to increasing imports. Furthermore, despite the use of conservative use-by dates, there are still 1 million cases of food poisoning (20,000 hospitalizations, 500 deaths, 1.5 billion GBP) every year in the UK alone due to spoiled foods. Low-cost technologies for monitoring spoilage can play an important role in reducing the amount of waste and preventing foodborne illnesses at the same time. In this 12-month project, an entirely new class of ultra-low-cost printed electrical gas sensors based on cellulose paper will be developed. This new versatile sensor technology, which exploits the intrinsic properties of paper, works at room temperature, is low power (in the order of micro watts), disposable, lightweight and compatible with current high-volume printing technologies. Our laboratory prototypes fabricated for producing the preliminary data for this grant application costed 0.005 GBP per sensor but the cost can be potentially driven down below ~0.0001 GBP through high-volume manufacturing, rendering the technology proposed, near "zero-cost". At this price point, these sensors can be placed in every food package, allowing monitoring of spoilage of foods. This would in turn prevent untimely disposal of food products while informing the consumer of spoiled items.In contrast to existing methods of detecting gases electrically using electronic materials (such as metal-oxide semiconductors - i.e. MOS - or organic semiconductors), this new technology exploits the effect of gases on the concentration of ions in the surface bound layer of water (adsorbed from the moisture in air) present on cellulose fibres, hence the term electroionic gas sensing. Unlike other technologies for sensing of gases, the technology proposed is particularly suitable for operation in environments with high relative humidity, which are known to reduce the sensing performance or lifetime of existing technologies (e.g., MOS). Our initial results show that this new sensor technology is capable of sensing NH3 (an important by-product of decomposition of protein rich foods such as meat) at concentrations below 4 ppm (the limit of detection to be determined in this project) - well within the relevant range for monitoring spoilage. Our pilot results for monitoring spoilage of raw meats also suggest that this technology is feasible.The final deliverable of this project is an elegant yet simple, fully characterized disposable Paper-based Printed Electroionic Gas Sensor (PES) capable of detecting food spoilage, focusing primarily on raw meats. In the future, our vision is to extent this technology to interface with RFID tags for wireless spoilage monitoring in homes, shops and food processing facilities.