A rapid portable self-test for COVID-19 intended to be as accurate as a PCR test without a prescription.

New nanosensor technology developed at Purdue University disrupts current diagnostics industry for multiple viruses

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How is Check4™ different from other COVID tests?

Check4™ — developed by IdentifySensors Biologics and Purdue University, is intended to be a rapid portable self-test for COVID-19 that is an accurate as a PCR test and sold without a prescription. Results from saliva are displayed within minutes on a smartphone app. Check4™ is intended to use newly developed nanosensors for convenient and highly accurate results.

Electronic readers send signals to smartphones to display results in minutes, anywhere, any time. The reusable reader is intended to cost about $130. Each COVID test cartridge is intended to cost less than $25. No prescriptions, no mailing samples and no waiting for laboratory results.

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A highly accurate and affordable over the counter COVID self-test for smartphone


Check4™ — a portable self-test intended to be as accurate as a PCR test in minutes without a prescription. A nanosensor cartridge interacts with saliva to produce a distinguishable electronic signal for positive or negative results with accuracy that rivals PCR tests. Results are displayed in minutes on a smartphone app, which automatically notifies health authorities.


Check4™ is intended to meet the gold-standard in COVID testing with minimal false positives and false negatives. The test is being developed at Purdue University by world-renowned scientists. It is intended to avoid the limitations of current molecular tests such as enzymatic reactions, amplification, sample preservation or sample transportation, which can introduce artifacts and raise the risk of false positives.


Check4™ is anticipated to cost less than $25 per test, which is six times less expensive than the average cost of a PCR test. Our approach avoids costly elements used by laboratory-based molecular tests such as enzymes and reagents that are in short supply. It also eliminates the need for laboratory technicians, diagnostic machines and personal protective equipment.

Check4™ Features

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An over-the-counter saliva test intended to produce highly accurate results without a prescription or doctor’s visit.

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Intended to meet the gold standard of PCR testing, including asymptomatic infections that rapid antigen tests miss. 

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Frequent Testing

Small portable readers intend to enable frequent, inexpensive self-testing, anywhere, any time.

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Disposable cartridges are intended to cost less than $25 without a prescription.

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Tests are intended to be programmed to detect any specific pathogens, including MRSA, SARS, Influenza and HIV.

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Electronic signals are sent to a smartphone app to display test results within minutes.

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How does Check4™ work?

Consumers buy a small, simple device online or from a retail store and download the free smartphone app. The device includes a reusable reader that transmits data to a smartphone and a single-use sensor cartridge. A saliva sample is placed in the sensor cartridge and signals are sent to the reader for processing. Test results are transmitted to a smartphone app within minutes.

Results Appear in Minutes on Your Smartphone – anywhere, anytime:

  • No nasal swabs
  • No delayed results
  • No prescriptions
  • No doctor visits
  • No laboratories
  • No waiting in lines
  • No mailing in samples
  • No high costs