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Physarum Sensor: Biosensor for Citizen Scientists

Periodic Reporting for period 1 - PhySense (Physarum Sensor: Biosensor for Citizen Scientists)

Reporting period: 2017-06-01 to 2018-08-31

Electrochemical biosensors currently dominate the field, but are focussed mainly on metabolite monitoring, while bio-affinity monitoring is carried out principally using optical techniques. However, both transducers find utility across the whole field, along with piezoelectric, thermometric, magnetic and micro-mechanical transducers. The emergence of semi-synthetic and synthetic receptors is yielding more robust, versatile and widely applicable sensors, while nano-materials are facilitating highly sensitive and convenient transduction of the resulting binding and catalytic events. Few if any sensoring devices incorporate living substrates because it is very difficult to keep the living substrate (e.g. micro-organisms, cell cultures, tissue) functioning in a non-sterile environment with a bandwidth of supporting devices. We proposed to develop a slime mould based sensor as the only ever marketable bio-sensor with living substrate which does not require sophisticated maintenance and can be operated by anyone.

Biosensor technology is based on a specific biological recognition element in combination with a transducer for signal processing. Since its inception, biosensors have been expected to play a significant analytical role in medicine, agriculture, food safety, homeland security, environmental and industrial monitoring. However, the commercialisation of biosensor technology has significantly lagged behind the research output as reflected by a plethora of publications and patenting activities. The rationale behind the slow and limited technology transfer could be attributed to cost considerations and some key technical barriers. Analytical chemistry has changed considerably, driven by automation, miniaturisation, and system integration with high throughput for multiple tasks. Such requirements pose a great challenge in biosensor technology which is often designed to detect one single or a few target analytes. Successful biosensors must be versatile to support interchangeable bio-recognition elements, and in addition miniaturisation must be feasible to allow automation for parallel sensing with ease of operation at a competitive cost. A significant upfront investment in research and development is a prerequisite in the commercialisation of biosensors. The progress in such endeavours is incremental with limited success, thus, the market entry for a new venture is very difficult unless a niche product can be developed with a considerable market volume.

Our goal was to manufacture, market and support open source an open hardware very low cost universal (chemical, tactile, optical) bio-sensor incorporating easy-to-maintain living substrate -- slime mould Physarum polycephalum. The Physarum sensors is based on exhaustive analysis of the slime mould oscillatory activity in PhyChip project. The goal was achieved via the following measurable objectives:
(1) Pre-production prototype, (2) Field trial with typical operators, (2) Robust data set in the matrices of interest.
Slime mould Physarum polycephalum is a large single cell easy to culture by scientist and hobbyists. We developed an effective and practical technology for using slime mould P. polycephalum as a living transducer in mechanical, optical and chemical sensors. The slime mould maps a wide range of optical stimuli, volatile chemicals, mechanical stimulations into a unique combination of frequency and amplitude of oscillations of its extracellular electrical potential. We developed a PhySense --- hybrid wetware-hardware biosensor --- comprised of the living slime mould and a cheap yet reliable analog-digital converted and amplifier. The working prototypes feature low cost electronics and bespoke software. Hardware and software, together with all protocols on culturing the slime mould and a range of possible experiments to implement, are available freely to academics and general public. Assembled devices of PhySense will be offered for a very affordable price after the project. The PhySense will allow citizen participants to leapfrog years of traditional research catapulting Europe in the driving seat of the exciting new scientific frontier of living technologies in sensing and computing.
The biosensors industry is now worth billions of United States dollars, the topic attracts the attention of national initiatives across the world and tens of thousands of papers have been published in the area. The biosensors is a ubiquitous technology of the future for health and the maintenance of wellbeing. Biosensors development is a continuous process and there is always room for improvement in the design and components of emerging biosensors. With the addition of more environmental contaminants which may be threat for humans and the overall ecosystem, the need for faster and more accurate biosensors will always at high-rise. Biosensors at present required to get the trust of potential consumers, keeping in mind that the acceptance of new manoeuvres is the best indicator of the success and achievement for an emerging technology.

Industry and agriculture are tapping into the benefits more capable sensors and instrumentation can provide. More capable sensors enable manufacturers to drive significant improvements in process and plant efficiency, product quality and safety. But while an increasing number of organisations are recognising the need to implement more sensors, or more capable sensors within their processes and facilities, deployment often proves challenging. PhySense will be the first ever living sensorial devices on the market. Cost-effective and eco-compatible sensing device applied to two relevant problem of the modern society, such as air pollution and use of chemicals in organic agriculture. Researcher, academics, school students and science enthusiasts will get a unique tool to develop interdisciplinary activities and get involved in gaining a larger knowledge far exceeding that of their field of specialization.

Extent of economic and/or societal benefits is as following. There are no biosensors (apart of glucose) on the market which general public and schools can afford. Our device, costing c. 30 EUR, will be an ultimate breakthrough in the niche of bio-sensing products. Complementary benefits are that the slime mould is a standard species for school experiments on light-avoidance and chemo-taxis, our device will allow schools to introduce subjects of non-linear media, wave-propagation in living substrates and physiology of myxomycetes. Moreover, as demonstrated in PhyChip one can make a self-routing wires, memristors (resistors with memory), transistors, electronic oscillators, robot controllers with slime mould. Thus a range of applications and research and educational experiments propagates far beyond sensing.
Physarum protoplasmic tube spanning electrodes
Slime mould in a Petri dish
PhySense units in action
Measuring of several Physarum samples in a butch