Gastrobot, meaning literally 'stomach robot', was a term coined in 1998 by the University of South Florida Institute's director, Dr. Stuart Wilkinson. A gastrobot is "...an intelligent machine (robot) that derives all its energy requirements from the digestion of real food." The gastrobot's energy intake may come in the form of carbohydrates, lipids etc., or may be a simpler source, such as alcohol.
The energy source commonly used for this robot is a mixture of carbohydrates and protein. The robot gets these molecules through a microbial fuel cell (MFC), which converts the food into gases and other potential energy. The gases and liquids help fuel things such as a hydrogen fuel cell, which helps create more energy—and other gases that help power the gastrobot's mechanics.
These robots might be able to perform certain types of so-called 'start and forget' missions, such as to help maintain a particular ecological environment by removing invasive species. They might use optic sensors inputs to artificial intelligence software to determine what they can eat for energy conversion.
Gastrobotics could allow users to deploy self-sustaining robots for extended times without human supervision. Common robots of today—powered by solar panels, batteries, or other energy sources—tend to become unreliable without human supervision for battery replacement, etc. Other robots must plug in to recharge, so they require constant access to an electrical outlet, which limits range. Solar powered robots are more independent but need a large surface area of solar panels to be efficient. This adds bulk and depends on weather conditions and clean panels to remain efficient. Gastrobotics might be able to live entirely off available natural resources. The main goal of this new technology is to produce robots that can go on missions where human supervision is not feasible or desirable. [1]
Some examples include
Gastrobotics energy sources mainly focuses on the use of a microbial fuel cell. Microbial fuel cells require an oxidation reduction reaction to generate electricity. A microbial fuel cell uses bacteria, which must be fed. The fuel cell typically contains two compartments, the anode and cathode terminals which are separated by an ion-exchange membrane.
First, in the anode chamber, the bacteria remove electrons from the organic material and pass the electrons to a carbon electrode. The electrons then move through the ion-exchange membrane to the cathode chamber, where they combine with protons and oxygen to form water. The electrons flowing from the anode into the cathode terminals generate electrical current and voltage. From this point, research is exploring using a hydrogen fuel cell to amplify the energy from the microbial fuel cell. The hydrogen fuel cell would use microbial fuel cell byproducts to create more energy without having to consume more material. Gastrobot requirements include:
The best fuel source for a gastrobot is anything high in carbohydrates. Vegetables, fruit, grains, insects, and foliage are good candidates. However, it can also consume organic waste products such as urine, anaerobic sludge (biodegradable waste and sewage), and landfill leachate. Meat can be a fuel, but contains too much fat to be efficient. [3]
The future of gastrobotics has many potential benefits to society.
The gastrobot is in its early development stages, and so faces many challenges:
As robots become more independent they must be more compliant. If a robot is out on a "mission" it must be sensitive to others around it instead of having a "complete task at all costs" mentality. [4]
Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outcome of a particular chemical change, or vice versa. These reactions involve electrons moving via an electronically-conducting phase between electrodes separated by an ionically conducting and electronically insulating electrolyte.
An electrochemical cell is a device that generates electrical energy from chemical reactions. Electrical energy can also be applied to these cells to cause chemical reactions to occur.
A fuel cell is the electrochemical cell that converts the chemical energy of a fuel and an oxidizing agent into electricity through a pair of redox reactions. Fuel cells are different from most batteries in requiring a continuous source of fuel and oxygen to sustain the chemical reaction, whereas in a battery the chemical energy usually comes from substances that are already present in the battery. Fuel cells can produce electricity continuously for as long as fuel and oxygen are supplied.
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity".
Redox is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state.
Direct-methanol fuel cells or DMFCs are a subcategory of proton-exchange fuel cells in which methanol is used as the fuel. Their main advantage is the ease of transport of methanol, an energy-dense yet reasonably stable liquid at all environmental conditions.
A solid oxide fuel cell is an electrochemical conversion device that produces electricity directly from oxidizing a fuel. Fuel cells are characterized by their electrolyte material; the SOFC has a solid oxide or ceramic electrolyte.
Artificial photosynthesis is a chemical process that biomimics the natural process of photosynthesis to convert sunlight, water, and carbon dioxide into carbohydrates and oxygen. The term artificial photosynthesis is commonly used to refer to any scheme for capturing and storing the energy from sunlight in the chemical bonds of a fuel. Photocatalytic water splitting converts water into hydrogen and oxygen and is a major research topic of artificial photosynthesis. Light-driven carbon dioxide reduction is another process studied that replicates natural carbon fixation.
Electrolysis of water is using electricity to split water into oxygen and hydrogen gas by electrolysis. Hydrogen gas released in this way can be used as hydrogen fuel, or remixed with the oxygen to create oxyhydrogen gas, for use in welding and other applications.
Direct-ethanol fuel cells or DEFCs are a category of fuel cell in which ethanol is fed directly into the cell. They have been used as a model to investigate a range of fuel cell concepts including the use of PEM.
Microbial fuel cell (MFC) is a type of bioelectrochemical fuel cell system that generates electric current by diverting electrons produced from the microbial oxidation of reduced compounds on the anode to oxidized compounds such as oxygen on the cathode through an external electrical circuit. MFCs produce electricity by using the electrons derived from biochemical reactions catalyzed by bacteria. MFCs can be grouped into two general categories: mediated and unmediated. The first MFCs, demonstrated in the early 20th century, used a mediator: a chemical that transfers electrons from the bacteria in the cell to the anode. Unmediated MFCs emerged in the 1970s; in this type of MFC the bacteria typically have electrochemically active redox proteins such as cytochromes on their outer membrane that can transfer electrons directly to the anode. In the 21st century MFCs have started to find commercial use in wastewater treatment.
An enzymatic biofuel cell is a specific type of fuel cell that uses enzymes as a catalyst to oxidize its fuel, rather than precious metals. Enzymatic biofuel cells, while currently confined to research facilities, are widely prized for the promise they hold in terms of their relatively inexpensive components and fuels, as well as a potential power source for bionic implants.
A solid oxide electrolyzer cell (SOEC) is a solid oxide fuel cell that runs in regenerative mode to achieve the electrolysis of water by using a solid oxide, or ceramic, electrolyte to produce hydrogen gas and oxygen. The production of pure hydrogen is compelling because it is a clean fuel that can be stored, making it a potential alternative to batteries, methane, and other energy sources. Electrolysis is currently the most promising method of hydrogen production from water due to high efficiency of conversion and relatively low required energy input when compared to thermochemical and photocatalytic methods.
Electromethanogenesis is a form of electrofuel production where methane is produced by direct biological conversion of electrical current and carbon dioxide.
A biobattery is an energy storing device that is powered by organic compounds. Although the batteries are still being tested before being commercially sold, several research teams and engineers are working to further advance the development of these batteries.
A microbial electrolysis cell (MEC) is a technology related to Microbial fuel cells (MFC). Whilst MFCs produce an electric current from the microbial decomposition of organic compounds, MECs partially reverse the process to generate hydrogen or methane from organic material by applying an electric current. The electric current would ideally be produced by a renewable source of power. The hydrogen or methane produced can be used to produce electricity by means of an additional PEM fuel cell or internal combustion engine.
Microbial electrosynthesis (MES) is a form of microbial electrocatalysis in which electrons are supplied to living microorganisms via a cathode in an electrochemical cell by applying an electric current. The electrons are then used by the microorganisms to reduce carbon dioxide to yield industrially relevant products. The electric current would ideally be produced by a renewable source of power. This process is the opposite to that employed in a microbial fuel cell, in which microorganisms transfer electrons from the oxidation of compounds to an anode to generate an electric current.
Geopsychrobacter electrodiphilus is a species of bacteria, the type species of its genus. It is a psychrotolerant member of its family, capable of attaching to the anodes of sediment fuel cells and harvesting electricity by oxidation of organic compounds to carbon dioxide and transferring the electrons to the anode.
Biological photovoltaics, also called biophotovoltaics or BPV, is an energy-generating technology which uses oxygenic photoautotrophic organisms, or fractions thereof, to harvest light energy and produce electrical power. Biological photovoltaic devices are a type of biological electrochemical system, or microbial fuel cell, and are sometimes also called photo-microbial fuel cells or “living solar cells”. In a biological photovoltaic system, electrons generated by photolysis of water are transferred to an anode. A relatively high-potential reaction takes place at the cathode, and the resulting potential difference drives current through an external circuit to do useful work. It is hoped that using a living organism as the light harvesting material, will make biological photovoltaics a cost-effective alternative to synthetic light-energy-transduction technologies such as silicon-based photovoltaics.
Microbial electrochemical technologies (METs) use microorganisms as electrochemical catalyst, merging the microbial metabolism with electrochemical processes for the production of bioelectricity, biofuels, H2 and other valuable chemicals. Microbial fuel cells (MFC) and microbial electrolysis cells (MEC) are prominent examples of METs. While MFC is used to generate electricity from organic matter typically associated with wastewater treatment, MEC use electricity to drive chemical reactions such as the production of H2 or methane. Recently, microbial electrosynthesis cells (MES) have also emerged as a promising MET, where valuable chemicals can be produced in the cathode compartment. Other MET applications include microbial remediation cell, microbial desalination cell, microbial solar cell, microbial chemical cell, etc.,.