Joe Davis. Bacterial Radio

Joe Davis (2011). Bacterial Radio, Bacterial Radio exhibits several bacterially-grown platinum/germanium electrical circuits (crystal radios) on glass substrates.



Conductors, insulators, semiconductors and other interesting things

Anything that is computerized or uses radio waves depends on semiconductors.

  • A semiconductor is a material with electrical conductivity due to electron flow (as opposed to ionic conductivity) intermediate in magnitude between that of a conductor and an insulator. Common semiconducting materials are crystalline solids. These include hydrogenated amorphous silicon and mixtures of arsenic, selenium and tellurium in a variety of proportions. Such compounds share with better known semiconductors intermediate conductivity and a rapid variation of conductivity. The electronic properties and the conductivity of a semiconductor can be changed in a controlled manner by adding very small quantities of other elements, called “dopants”, to the intrinsic material. In crystalline silicon typically this is achieved by adding impurities of boron or phosphorus to the melt
  • A mineral is a naturally occurring substance, representable by a chemical formula, usually solid and inorganic, carries a crystal structure. The silicate minerals compose over 90% of the Earth's crust.
  • A crystal is a solid material whose constituents, such as atoms, molecules or ions, are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.
  • Carbon's abundance, its unique diversity of organic compounds, and its unusual ability to form polymers at the temperatures commonly encountered on Earth enables this element to serve as a common element of all known life. It is the second most abundant element in the human body by mass (about 18.5%) after oxygen.
  • Silicon is most widely distributed in dusts, sands, planetoids, and planets as various forms of silicon dioxide (silica) or silicates. Over 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust (about 28% by mass) after oxygen.
  • Silicate, or silicic acid (H4SiO4), is an important nutrient in the ocean. Unlike the other major nutrients such as phosphate, nitrate, or ammonium, which are needed by almost all marine plankton, silicate is an essential chemical requirement for very specific biota, including diatoms, radiolaria, silicoflagellates, and siliceous sponges. These organisms extract dissolved silicate from open ocean surface waters for the buildup of their particulate silica (SiO2), or opaline, skeletal structures (i.e. the biota’s hard parts).
  • Biogenic silica (bSi) forms one of the most widespread biogenic minerals. For example, microscopic particles of silica can be found in bacteria, animals and plants. In order to conduct voltage for his bacterial radio Joe Davis used orange marine puffball sponges (Tethya aurantia). Silica is an amorphous metal oxide formed by complex inorganic polymerization processes.

Crystal radio

“A crystal radio is a basic resonant circuit requiring only induction, capacitance and a radio “crystal,” a mineral semiconductor used to convert received radio signals into DC electrical signals that can be resolved with headphones as sound. These simple circuits require no batteries, tubes or transistors and operate with only the difference in voltage between the antenna and the ground.” (bacterial radio,

AM Frequency and calculation

Crystal radio circuit