A $10 Chip That Could Put a Medical Lab on Your Wrist
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Smartwatches already track your heart rate and steps. What they can't do well is measure chemistry, such as sugar in your blood or alcohol in your system, without a needle or a lab. A team at the University of Cambridge thinks a tiny wearable spectrometer costing about $10 could change that. In tests published in Nature Photonics, their chip matched or beat bulky benchtop instruments on several measurements.
What a spectrometer does
A spectrometer analyzes light after it passes through or bounces off something. Different molecules absorb different colors, including invisible near-infrared light, leaving a unique fingerprint. Read the fingerprint and you can tell what a material is and how much of a substance it contains.
The problem has always been size. Lab spectrometers are precise but big and expensive. Shrinking them usually sacrifices range, resolution or accuracy.
The Cambridge trick: do the math with light
The new device, called a convolutional spectrometer, takes a different route. Instead of splitting light into its colors or running heavy reconstruction algorithms, it performs a mathematical operation called convolution directly on the incoming light.
It does this with a chain of optical components with repeating responses, such as tiny interferometers or ring resonators, built on a silicon nitride photonic chip. A fast Fourier transform then recovers the spectrum. Lead author Dr Chunhui Yao says going back to the underlying mathematics gave them a cleaner way to read spectra, with high precision, strong tolerance to noise and very little computing overhead.
The numbers
| Feature | Result |
|---|---|
| Approximate cost | about $10 |
| Size | a few centimeters across |
| Wavelength range | 1,200–1,700 nm (near-infrared) |
| Measurement time | under one second |
| Material identification | 100% success on plastics, medicines, coffee, flour and tea |
| Concentration accuracy | about 0.01% in test solutions |
| Operating temperature | −20 °C to 80 °C |
The design can also grow: adding more optical stages can extend its range and increase its resolution sharply, without redesigning the whole system.
The health tests
Under conditions designed to mimic the body, the chip measured skin moisture, blood alcohol, blood lactate and blood glucose. The team also tracked glucose non-invasively in one volunteer over an extended period.
That is promising for people with diabetes, who often prick their fingers or wear sensor patches with tiny needles. But it is an early result from one participant. Medical devices need large clinical trials and regulatory approval before anyone should rely on them.
Beyond healthcare
The team, which has spun out a startup called GlitterinTech, sees uses far outside medicine:
- Factories checking product quality continuously on the line
- Food testing for freshness and authenticity
- Recycling sorting plastics by type
- Environment monitoring water and soil
Project lead Prof Qixiang Cheng says the goal is to make spectrometry as common as temperature or motion sensing in everyday devices.
Sources
Frequently asked questions
What is a wearable spectrometer?
A tiny optical sensor that reads the light fingerprint of substances, small enough to fit into wearables or phones.
Can the Cambridge chip measure glucose without needles?
It tracked glucose non-invasively in one participant, but much more testing is needed before medical use.
How much does the sensor cost?
Around $10, according to the researchers.
How accurate is it?
It identified test materials with 100% success and measured solution concentrations to about 0.01%.
When will it be in smartwatches?
No date has been announced; the technology still needs product development and medical validation.