What is a biochip?

Reference guide written and published by biochip.com. Draft, not yet independently reviewed; last substantive update September 7, 2026.

A biochip is a small, engineered surface or device that carries out many biological measurements at once, or carries out a biological analysis that used to need a bench full of equipment. The word is an umbrella, not a single technology. It covers glass slides printed with thousands of DNA spots, plastic cartridges that move a drop of blood through channels thinner than a hair, silicon sensors that read chemistry as an electrical signal, and semiconductor chips that sequence genomes. What these have in common is the borrowing of ideas from the microelectronics industry, above all miniaturization and parallelism, and applying them to biology.

The four main kinds of biochip

Microarrays

The first devices to be called biochips were DNA microarrays: glass or silicon slides carrying a grid of thousands to millions of tiny spots, each holding a known DNA sequence. A sample labelled with a fluorescent dye is washed over the slide; wherever the sample's DNA matches a spot, it binds, and a scanner reads the pattern of light. Two papers defined the field. In 1991 Fodor and colleagues showed that light-directed chemistry could build arrays of different molecules at defined positions on a surface (Fodor et al., Science 1991), the basis of the Affymetrix GeneChip. In 1995 Schena, Brown and colleagues printed complementary DNA onto glass to measure the expression of many genes in one experiment (Schena et al., Science 1995). Protein, antibody and tissue microarrays followed the same logic with different molecules on the spots.

Lab-on-a-chip and microfluidic devices

A lab-on-a-chip moves and processes tiny volumes of liquid through microscopic channels, valves and chambers so that sample preparation, reaction and detection happen in one device. The concept was set out by Manz, Graber and Widmer in 1990 under the name miniaturized total analysis system (Manz et al., 1990). The underlying discipline is microfluidics, the physics and engineering of fluids at that scale. Our guides on microfluidics and lab-on-a-chip cover both in more depth.

Biosensor chips

A biosensor pairs a biological recognition element, such as an enzyme, antibody or DNA strand, with a transducer that converts the recognition event into a measurable signal, usually electrical or optical. When the transducer is a microfabricated electrode or photonic structure, the result is often called a biosensor chip. The glucose test strip is the most widely used example. See the biosensors guide.

Semiconductor sequencing and detection chips

Some biochips are literally integrated circuits. Ion Torrent sequencing reads DNA by detecting the hydrogen ion released each time a nucleotide is incorporated, using an array of millions of ion-sensitive field-effect transistors on a standard CMOS chip (Rothberg et al., Nature 2011). Other CMOS biochips detect binding events electrically, run many electrochemical measurements in parallel, or image cells without lenses.

Why miniaturize biology at all?

Three reasons come up in nearly every application. Less sample and reagent: a microliter costs less than a milliliter, and some samples, such as a newborn's blood or a rare tumor biopsy, are scarce. Parallelism: a microarray asks tens of thousands of questions in one experiment, and a sequencing chip performs millions of reactions at once. Portability and speed: reactions in small volumes reach temperature and mix quickly, and a cartridge can be carried to the patient instead of shipping the patient's sample to a laboratory. Whitesides' 2006 review remains a clear account of these motivations and of how the field grew out of analytical chemistry, defence research and molecular biology (Whitesides, Nature 2006).

What biochips are used for

• Research: gene-expression profiling, genotyping, protein interaction screening, single-cell analysis and drug screening.
• Clinical diagnostics: cartridge-based molecular tests for infections, blood-gas and electrolyte analyzers, glucose monitoring, and companion diagnostics that guide cancer treatment.
• Sequencing: flow cells and semiconductor chips are the physical substrate of most modern DNA sequencing.
• Environmental, food and biodefence testing: field-portable detection of pathogens and toxins.
• Tissue models: organ-on-a-chip devices that culture living cells under controlled flow, covered in our organ-on-a-chip guide.

Limits and common misunderstandings

A biochip is rarely the whole instrument. Most chips need a reader, pumps, optics or electronics around them, and that surrounding hardware is often where cost, size and reliability problems live. Sample preparation is usually the hard part. Getting blood, sputum or soil into a form a chip can analyse is often more work than the analysis itself. Miniaturization does not guarantee accuracy. Smaller volumes contain fewer molecules, so sensitivity, contamination and statistics all become more demanding. Manufacturing at scale is a separate problem from demonstrating a device in a research lab, and it is where many promising academic chips stall.

Finally, the word itself is loose. Vendors and headlines apply "biochip" to implanted RFID tags, neural implants and brain-computer interfaces, which are different technologies with different questions attached. On this site, biochip means a device for biological or chemical analysis, and each article links to its original source so you can see exactly which kind is being described.

Related terms

• Microarray: an ordered grid of probe molecules on a surface, read by fluorescence or electrical signal.
• Microfluidics: handling fluids in channels of roughly 1 to 1000 micrometres; the engineering base of lab-on-a-chip devices.
• Lab-on-a-chip / micro total analysis system (µTAS): a device that integrates several laboratory steps.
• Biosensor: a bioreceptor plus a transducer that produces a measurable signal.
• Point-of-care test: a test performed near the patient rather than in a central laboratory; many are biochips, but not all biochips are point-of-care tests.