Organ-on-a-chip explained

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

An organ-on-a-chip is a microfluidic device in which living human cells are cultured in channels that reproduce some of the physical and chemical conditions of an organ: the flow of blood or air, mechanical stretching, tissue-to-tissue interfaces, and chemical gradients. It is not a miniature organ. It is a model of one or a few organ-level functions, built precisely enough to ask questions that flat cell cultures cannot answer and that animal experiments answer only imperfectly. Organ chips sit at the intersection of microfluidics, stem-cell biology and tissue engineering, and they are one of the most active areas of biochip research.

The device that defined the field

In 2010 Donald Ingber's group at the Wyss Institute described a lung-on-a-chip: two parallel microchannels separated by a thin, porous, flexible membrane, with human lung alveolar cells on one side and capillary endothelial cells on the other (Huh et al., Science 2010). Air flowed over the alveolar cells and culture medium over the vascular cells, and vacuum applied to side chambers stretched the membrane rhythmically, imitating breathing. The chip reproduced inflammatory responses to bacteria and showed that breathing motion increased the uptake of nanoparticles into the "bloodstream", an effect that flat cultures missed. That combination of two tissues, an interface, flow and mechanical forces became the template for chips modelling gut, liver, kidney, blood-brain barrier, skin, bone marrow and heart tissue.

How an organ chip is built

• Substrate: most research chips are moulded PDMS, which is transparent and flexible but absorbs drugs; commercial and newer academic systems use plastics or glass to avoid that.
• Cells: primary human cells, cell lines, or cells differentiated from induced pluripotent stem cells, which allow patient-specific chips.
• Extracellular matrix: coatings or gels that give cells something realistic to attach to.
• Perfusion: pumps or gravity move medium through the channels, delivering nutrients, removing waste and applying the shear stress that cells in vessels normally feel.
• Sensors and imaging: transparency allows live microscopy; integrated electrodes can measure barrier integrity or electrical activity.

Connecting several organ chips in sequence, so that medium passes from a gut chip to a liver chip to a kidney chip, produces a body-on-a-chip or multi-organ system intended to model how a drug is absorbed, metabolised and cleared. Bhatia and Ingber's 2014 review describes the design principles and the range of organs modelled by then (Bhatia and Ingber, Nature Biotechnology 2014).

What organ chips are used for

Drug toxicity. Liver and kidney chips are used to detect toxic effects that animal models miss because of species differences in metabolism. Disease modelling. Chips built with cells from patients can reproduce features of genetic diseases, inflammatory bowel disease, or tumour-vessel interactions. Infection. Airway chips were used to study influenza and SARS-CoV-2 and to screen existing drugs against them. Personalised medicine. Tumour or gut chips seeded with a patient's own cells have been used experimentally to test treatment responses. Ingber's 2022 review summarises this work and the evidence for each application (Ingber, Nature Reviews Genetics 2022).

Regulation: what changed in 2022

In the United States, the FDA Modernization Act 2.0, signed into law on 29 December 2022, removed the statutory requirement that new drugs be tested in animals before human trials and explicitly allows alternatives such as cell-based assays, organ chips and computer models to be used where appropriate (S.5002, 117th Congress). The law permits, rather than mandates, these methods; regulators still decide case by case what evidence is sufficient. Qualifying an organ chip for a specific regulatory use requires demonstrating reproducibility and predictive value, and that process is ongoing for most chip types.

Limits, stated plainly

A chip models a function, not an organ. There is no immune system unless one is added, no hormonal signalling from distant organs, and no long-term ageing. Cell sourcing is a bottleneck: primary human cells vary between donors and are scarce, and stem-cell-derived cells are often immature. Reproducibility between laboratories has been a recurring concern, which is why standardisation efforts and commercial platforms have emphasised it. Throughput is low and cost per experiment high compared with cell culture in plates. PDMS absorption can make drug concentrations in the chip differ from what was dosed. And validation against human outcomes, the evidence that a chip result predicts what happens in patients, exists for some chips and endpoints but is far from universal. Organ chips complement animal studies and organoids; claims that they have replaced either should be read against the specific evidence offered.

Related terms

• Organoid: a self-organising three-dimensional cluster of cells grown from stem cells; often used inside organ chips, but by itself has no controlled flow or defined interfaces.
• Microphysiological system (MPS): the broader regulatory and academic term covering organ chips, organoids and related in-vitro models.
• New approach methodology (NAM): the regulatory umbrella term for non-animal testing methods.
• Induced pluripotent stem cells (iPSCs): adult cells reprogrammed to an embryonic-like state, from which organ-specific cells can be derived.