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51-862: Betavoltaic power sources (and the related technology of alphavoltaic power sources) are particularly well-suited to low-power electrical applications where long life of the energy source is needed, such as implantable medical devices or military and space applications. Betavoltaics were invented in the 1970s. Some pacemakers in the 1970s used betavoltaics based on promethium , but were phased out as cheaper lithium batteries were developed. Early semiconducting materials weren't efficient at converting electrons from beta decay into usable current, so higher energy, more expensive—and potentially hazardous— isotopes were used. The more efficient semiconducting materials used as of 2019 can be paired with relatively benign isotopes such as tritium, which produce less radiation. The Betacel , developed by Larry C. Olsen ,

102-422: A conductor , thus creating an electrostatic potential . Without a dissipation mode the voltage can increase up to the energy of the radiated particles, which may range from several kilovolts (for beta radiation) up to megavolts (alpha radiation). The built up electrostatic energy can be turned into usable electricity in one of the following ways. A direct-charging generator consists of a capacitor charged by

153-400: A photovoltaic cell , except that they convert infrared light (rather than visible light ) emitted by a hot surface, into electricity. Thermophotovoltaic cells have an efficiency slightly higher than thermoelectric couples and can be overlaid on thermoelectric couples, potentially doubling efficiency. The University of Houston TPV Radioisotope Power Conversion Technology development effort

204-411: A piezoelectric material or through a linear generator. Milliwatts of power are produced in pulses depending on the charge rate, in some cases multiple times per second (35 Hz). A radiovoltaic (RV) device converts the energy of ionizing radiation directly into electricity using a semiconductor junction , similar to the conversion of photons into electricity in a photovoltaic cell . Depending on

255-440: A Russian design based on 2-micron thick nickel-63 slabs sandwiched between 10 micron diamond layers was introduced. It produced a power output of about 1 μW at a power density of 10  μW /cm. Its energy density was 3.3 kWh/kg. The half-life of nickel-63 is 100 years. In 2019 a paper indicated the viability of betavoltaic devices in high-temperature environments in excess of 733 K (460 °C; 860 °F) like

306-441: A competitive threat, although one may be able to learn from them and adapt their techniques. A tacit assumption of many is that TTM and product quality are opposing attributes of a development process. TTM may be improved (shortened) by skipping steps of the development process, thus compromising product quality. For those who use highly structured development processes such as Phase–gate model or Six Sigma , product development

357-487: A hot electrode, which thermionically emits electrons over a space-charge barrier to a cooler electrode, producing a useful power output. Caesium vapor is used to optimize the electrode work functions and provide an ion supply (by surface ionization ) to neutralize the electron space charge . A radioisotope thermoelectric generator (RTG) uses thermocouples . Each thermocouple is formed from two wires of different metals (or other materials). A temperature gradient along

408-415: A larger voltage (or current) from the same heat source, as heat flows from the hot ends to the cold ends. Metal thermocouples have low thermal-to-electrical efficiency. However, the carrier density and charge can be adjusted in semiconductor materials such as bismuth telluride and silicon germanium to achieve much higher conversion efficiencies. Thermophotovoltaic (TPV) cells work by the same principles as

459-400: A late product launch in any industry can negatively impact revenues—from reducing the window of opportunity to generate revenues to causing the product to become obsolete faster. There are no standards for measuring TTM, and measured values can vary greatly. First, there is great variation in how different organizations define the start of the period. For example, in the automotive industry

510-524: A particle accelerator is more difficult to obtain than a fission product easily extracted from spent nuclear fuel . Plutonium-238 must be deliberately produced via neutron irradiation of Neptunium-237 but it can be easily converted into a stable plutonium oxide ceramic. Strontium-90 is easily extracted from spent nuclear fuel but must be converted into the perovskite form strontium titanate to reduce its chemical mobility, cutting power density in half. Caesium-137, another high yield nuclear fission product,

561-504: A period of many years. For tritium devices, the half-life is 12.32 years. In device design, one must account for what battery characteristics are required at end-of-life, and ensure that the beginning-of-life properties take into account the desired usable lifetime. Liability connected with environmental laws and human exposure to tritium and its beta decay must also be taken into consideration in risk assessment and product development . Naturally, this increases both time-to-market and

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612-534: A radioactive material as a power source, the beta particles are low energy and easily stopped by a few millimetres of shielding . With proper device construction (that is, proper shielding and containment), a betavoltaic device would not emit dangerous radiation. Leakage of the enclosed material would engender health risks, just as leakage of the materials in other types of batteries (such as lithium , cadmium and lead ) leads to significant health and environmental concerns. Safety can be further increased by transforming

663-497: A semiconductor junction to produce electrical energy from energetic alpha particles . Betavoltaic devices use a semiconductor junction to produce electrical energy from energetic beta particles ( electrons ). A commonly used source is the hydrogen isotope tritium , which is employed in City Labs' NanoTritium batteries . Betavoltaic devices are particularly well-suited to low-power electrical applications where long life of

714-420: A single EHP by a beta-particle is known to scale linearly with the bandgap as E E H P = A E g + B {\textstyle E_{EHP}=AE_{g}+B} with A and B depending on the semiconductor characteristics. Atomic battery#Alphavoltaic conversion An atomic battery , nuclear battery , radioisotope battery or radioisotope generator uses energy from

765-488: A source of beta particle electrons (either Carbon-14 or nickel-63 ) sandwiched between two thin crystallographic diamond semiconductor layers. The Chinese startup claims to have the miniature device in the pilot testing stage. Unveiled in January 2024, it is allegedly generating 100 microwatts of power and a voltage of 3V and has a lifetime of 50 years without any need for charging or maintenance. Betavolt claims it to be

816-432: Is aiming at combining thermophotovoltaic cells concurrently with thermocouples to provide a 3- to 4-fold improvement in system efficiency over current thermoelectric radioisotope generators. A Stirling radioisotope generator is a Stirling engine driven by the temperature difference produced by a radioisotope. A more efficient version, the advanced Stirling radioisotope generator , was under development by NASA , but

867-469: Is capable of radio frequency transmission, allowing MEMS devices to communicate with one another wirelessly. These micro-batteries are very light and deliver enough energy to function as power supply for use in MEMS devices and further for supply for nanodevices. The radiation energy released is transformed into electric energy, which is restricted to the area of the device that contains the processor and

918-627: Is often viewed as a clearly defined sequence of steps to be followed. Skipping a step—due to perceived time pressure, for example—may not only undercut quality but can ultimately lengthen TTM if the organization must complete or repeat the step later. Other organizations operate more aggressively, recognizing that not all steps need to be completed for every project. Furthermore, they actively apply tools and techniques that will shorten or overlap steps, cut decision-making time, and automate activities. Many such tools and techniques are available (see References below). Organizations pursue TTM improvement for

969-463: Is rarely used in atomic batteries because it is difficult to convert into chemically inert substances. Another undesirable property of Cs-137 extracted from spent nuclear fuel is that it is contaminated with other isotopes of Caesium which reduce power density further. In the field of microelectromechanical systems ( MEMS ), nuclear engineers at the University of Wisconsin, Madison have explored

1020-622: The decay of a radioactive isotope to generate electricity . Like a nuclear reactor , it generates electricity from nuclear energy, but it differs by not using a chain reaction . Although commonly called batteries , atomic batteries are technically not electrochemical and cannot be charged or recharged. Although they are very costly, they have extremely long lives and high energy density , so they are typically used as power sources for equipment that must operate unattended for long periods, such as spacecraft , pacemakers , underwater systems, and automated scientific stations in remote parts of

1071-456: The fuzzy front end , and this stage can consume a great deal of time. Even though the fuzzy front end is difficult to measure, it must be included in TTM measurements for effective TTM management. Next, definitions of the end of the TTM period vary. Those who look at product development as engineering say the project is finished when engineering department transfers it to manufacturing. Others define

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1122-410: The 2010s but were proposed as early as 1981. A gammavoltaic effect has been reported in perovskite solar cells . Another patented design involves scattering of the gamma particle until its energy has decreased enough to be absorbed in a conventional photovoltaic cell. Gammavoltaic designs using diamond and Schottky diodes are also being investigated. In a radiophotovoltaic (RPV) device

1173-582: The already high cost associated with tritium. A 2007 report by the UK government's Health Protection Agency Advisory Group on Ionizing Radiation declared the health risks of tritium exposure to be double those previously set by the International Commission on Radiological Protection located in Sweden. As radioactive decay cannot be stopped, sped up or slowed down, there is no way to "switch off"

1224-413: The battery or regulate its power output. For some applications this is irrelevant, but others will need a backup chemical battery to store energy when it isn't needed for when it is. This reduces the advantage of high power density. Betavoltaic nuclear batteries can be purchased commercially. Devices available as per 2012 included a 100 μW tritium-powered device weighing 20 grams Although betavoltaics use

1275-474: The betavoltaic device doubles as a radioisotope heater unit it is in effect a cogeneration plant and achieves much higher total efficiencies as much of the waste heat is useful. Similar to photovoltaics , the Shockley–Queisser limit also imposes an absolute limit for a single bandgap betavoltaic device. Since the highest energy that can possibly be extracted from a single EHP is the bandgap energy,

1326-587: The circuit for longer than the 88-year halflife of the plutonium-238. The last of these units was implanted in 1988, as lithium-powered pacemakers, which had an expected lifespan of 10 or more years without the disadvantages of radiation concerns and regulatory hurdles, made these units obsolete. Betavoltaic batteries are also being considered as long-lasting power sources for lead-free pacemakers. Atomic batteries use radioisotopes that produce low energy beta particles or sometimes alpha particles of varying energies. Low energy beta particles are needed to prevent

1377-403: The conclusion as when they ship the first copy of the new product or when a customer buys it. High-volume industries will often define the end point in terms of reaching a certain production volume, such as a million units per month. Finally, TTM measurements vary greatly depending on complexity –- complexity of the product itself, the technologies it incorporates, its manufacturing processes, or

1428-544: The conversion efficiency. Medtronic and Alcatel developed a plutonium-powered pacemaker , the Numec NU-5, powered by a 2.5 Ci slug of plutonium 238, first implanted in a human patient in 1970. The 139 Numec NU-5 nuclear pacemakers implanted in the 1970s are expected to never need replacing, an advantage over non-nuclear pacemakers, which require surgical replacement of their batteries every 5 to 10 years. The plutonium "batteries" are expected to produce enough power to drive

1479-542: The current of charged particles from a radioactive layer deposited on one of the electrodes. Spacing can be either vacuum or dielectric . Negatively charged beta particles or positively charged alpha particles , positrons or fission fragments may be utilized. Although this form of nuclear-electric generator dates back to 1913, few applications have been found in the past for the extremely low currents and inconveniently high voltages provided by direct-charging generators. Oscillator/transformer systems are employed to reduce

1530-423: The development period starts when the product concept is approved. Other organizations realize that little will happen until the project is staffed, which can take a long time after approval if developers are tied up on existing projects. Therefore, they consider the start point when the project is fully staffed. The initial part of a project—before approval has been given or full staffing is allocated—has been called

1581-506: The early 1950s, many types and methods have been designed to extract electrical energy from nuclear sources. The scientific principles are well known, but modern nano-scale technology and new wide-bandgap semiconductors have allowed the making of new devices and interesting material properties not previously available. Nuclear batteries can be classified by their means of energy conversion into two main groups: thermal converters and non-thermal converters . The thermal types convert some of

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1632-531: The energy conversion is indirect: the emitted particles are first converted into light using a radioluminescent material (a scintillator or phosphor ), and the light is then converted into electricity using a photovoltaic cell . Depending on the type of particle targeted, the conversion type can be more precisely specified as alphaphotovoltaic (APV or α-PV), betaphotovoltaic (BPV or β-PV) or gammaphotovoltaic (GPV or γ-PV). Radiophotovoltaic conversion can be combined with radiovoltaic conversion to increase

1683-463: The energy source is needed, such as implantable medical devices or military and space applications. The Chinese startup Betavolt claimed in January 2024 to have a miniature device in the pilot testing stage. It is allegedly generating 100 microwatts of power and a voltage of 3V and has a lifetime of 50 years without any need for charging or maintenance. Betavolt claims it to be the first such miniaturised device ever developed. It gains its energy from

1734-463: The first such miniaturised device ever developed. It gains its energy from a sheet of nickel-63 located in a module the size of a very small coin. The isotope decays into stable, non-radioactive Cu-63 , which pose no additional environmental threat. As radioactive material emits radiation, it slowly decreases in activity (refer to half-life ). Thus, over time a betavoltaic device will provide less power. For practical devices, this decrease occurs over

1785-569: The heat generated by the nuclear decay into electricity; an example is the radioisotope thermoelectric generator (RTG), often used in spacecraft. The non-thermal converters, such as betavoltaic cells , extract energy directly from the emitted radiation, before it is degraded into heat; they are easier to miniaturize and do not need a thermal gradient to operate, so they can be used in small machines. Atomic batteries usually have an efficiency of 0.1–5%. High-efficiency betavoltaic devices can reach 6–8% efficiency. A thermionic converter consists of

1836-525: The isotope nickel-63 , held in a module the size of a very small coin. As it is consumed, the nickel-63 decays into stable, non-radioactive isotopes of copper, which pose no environmental threat. It contains a thin wafer of nickel-63 providing beta particle electrons sandwiched between two thin crystallographic diamond semiconductor layers. Gammavoltaic devices use a semiconductor junction to produce electrical energy from energetic gamma particles (high-energy photons ). They have only been considered in

1887-426: The length of each wire produces a voltage gradient from one end of the wire to the other; but the different materials produce different voltages per degree of temperature difference. By connecting the wires at one end, heating that end but cooling the other end, a usable, but small (millivolts), voltage is generated between the unconnected wire ends. In practice, many are connected in series (or in parallel) to generate

1938-450: The micro-battery that supplies it with energy. Time to market In commerce , time to market ( TTM ) is the length of time it takes from a product being conceived until its being available for sale. The reason that time to market is so important is that being late erodes the addressable market into which producers have to sell their product. A common assumption is that TTM matters most for first-of-a-kind products, but actually

1989-562: The need for reliability above all else in many applications of betavoltaics, comparatively low efficiencies are acceptable. Current technology allows for single digit percentages of energy conversion efficiency from beta particle input to electricity output, but research into higher efficiency is ongoing. By comparison thermal efficiency in the range of 30% is considered relatively low for new large scale thermal power plants and advanced combined cycle power plants achieve 60% and more efficiency if measured by electricity output per heat input. If

2040-499: The organizational complexity of the project (for example, outsourced components). New-to-the-world products are much slower than derivatives of existing products. Some companies have been successful in putting their products into categories of newness, but establishing levels of complexity remains elusive. Although TTM can vary widely, all that matters is an organization's TTM capability relative to its direct competitors. Organizations in other industries may be much faster, but do not pose

2091-430: The possibilities of producing minuscule batteries which exploit radioactive nuclei of substances such as polonium or curium to produce electric energy. As an example of an integrated, self-powered application, the researchers have created an oscillating cantilever beam that is capable of consistent, periodic oscillations over very long time periods without the need for refueling. Ongoing work demonstrate that this cantilever

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2142-469: The production of high energy penetrating Bremsstrahlung radiation that would require heavy shielding. Radioisotopes such as tritium , nickel -63, promethium -147, and technetium -99 have been tested. Plutonium -238, curium -242, curium -244 and strontium -90 have been used. Besides the nuclear properties of the used isotope, there are also the issues of chemical properties and availability. A product deliberately produced via neutron irradiation or in

2193-453: The radioisotope used into a chemically inert and mechanically stable form, which reduces the risk of dispersal or bioaccumulation in case of leakage. Due to the high energy density of radioisotopes (Radioisotopes have orders of magnitude higher energy density than chemical energy sources, but much lower power density. The power density of a radioisotope is inversely proportional to its half-life. Shorter half-life = higher power density.) and

2244-563: The radium to the inside surface of the sphere. As late as 1945 the Moseley model guided other efforts to build experimental batteries generating electricity from the emissions of radioactive elements. Electromechanical atomic batteries use the buildup of charge between two plates to pull one bendable plate towards the other, until the two plates touch, discharge, equalizing the electrostatic buildup, and spring back. The mechanical motion produced can be used to produce electricity through flexing of

2295-462: The surface of Venus . Betavoltaics directly convert the kinetic energy of beta particles into electrical energy using semiconductor junctions. Unlike traditional nuclear reactors, which generate heat and then convert it to electricity, betavoltaics offer non-thermal conversion. A prototype betavoltaic battery announced in early 2024 by the Betavolt company of China contains a thin wafer providing

2346-472: The type of radiation targeted, these devices are called alphavoltaic (AV, αV), betavoltaic (BV, βV) and/or gammavoltaic (GV, γV). Betavoltaics have traditionally received the most attention since (low-energy) beta emitters cause the least amount of radiative damage, thus allowing a longer operating life and less shielding. Interest in alphavoltaic and (more recently) gammavoltaic devices is driven by their potential higher efficiency. Alphavoltaic devices use

2397-480: The ultimate efficiency of a beta-battery can be estimated as: η m a x = E g E E H P {\displaystyle \eta _{max}={E_{g} \over E_{EHP}}} where E g {\textstyle E_{g}} and E E H P {\textstyle E_{EHP}} are semiconductor band gap and electron-hole pair creation energy respectively. The energy to generate

2448-452: The voltages, then rectifiers are used to transform the AC power back to direct current. English physicist H. G. J. Moseley constructed the first of these. Moseley's apparatus consisted of a glass globe silvered on the inside with a radium emitter mounted on the tip of a wire at the center. The charged particles from the radium created a flow of electricity as they moved quickly from

2499-414: The world. Nuclear batteries began in 1913, when Henry Moseley first demonstrated a current generated by charged-particle radiation. In the 1950s and 1960s, this field of research got much attention for applications requiring long-life power sources for spacecraft. In 1954, RCA researched a small atomic battery for small radio receivers and hearing aids. Since RCA's initial research and development in

2550-479: Was cancelled in 2013 due to large-scale cost overruns. Non-thermal converters extract energy from emitted radiation before it is degraded into heat. Unlike thermoelectric and thermionic converters their output does not depend on the temperature difference. Non-thermal generators can be classified by the type of particle used and by the mechanism by which their energy is converted. Energy can be extracted from emitted charged particles when their charge builds up in

2601-598: Was one of the earliest and most successful commercialized betavoltaic batteries, and would inform the design of modern betavoltaic devices such as NanoTritium batteries . The primary use for betavoltaics is for remote and long-term use, such as spacecraft requiring electrical power for a decade or two. Recent progress has prompted some to suggest using betavoltaics to trickle-charge conventional batteries in consumer devices, such as cell phones and laptop computers . As early as 1973, betavoltaics were suggested for use in long-term medical devices such as pacemakers . In 2018

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