CMOS-Based Multiplexed NMR Acquisition toward High-Throughput Spectroscopy

Chemical analysis often feels like a race against time, especially when scientists need to understand the composition of hundreds or thousands of different samples. One of the most powerful tools for this job is nuclear magnetic resonance, a technique that uses strong magnetic fields and radio waves to reveal the precise structure of molecules. It is a gentle method that does not destroy the sample, allowing researchers to see exactly how atoms are arranged and how they interact. However, the traditional way of using this technology is slow. Standard machines are designed to look at one sample at a time, and even when they can look at multiple samples, the equipment required to listen to them all simultaneously becomes bulky, expensive, and tangled with a mess of cables. This bottleneck limits how fast scientists can screen new drugs or study complex biological mixtures, creating a pressing need for a way to speed up the process without sacrificing the quality of the data.

A team of researchers at the Karlsruhe Institute of Technology in Germany has developed a new approach to solve this problem by shrinking the complex electronics needed for parallel detection into a tiny computer chip. Their work focuses on a method called multiplexing, which allows multiple radio signals to travel down a single wire at the same time without interfering with each other. To test this idea, they built a custom chip using standard silicon manufacturing technology, measuring just 3 millimeters by 4 millimeters. This small device acts as a traffic controller for radio waves, taking the signals from four different sample detectors and combining them into one single stream that can be sent to a computer for analysis. By doing this, they eliminated the need for four separate receiver ports and the heavy bundle of cables that usually connects them, effectively reducing the cost and complexity of the hardware by a factor of four.

The researchers put their system to the test in two different scenarios to see if it could handle real-world conditions. In the first experiment, they used a specialized probe containing four separate detectors, each holding a different liquid sample. Two of the detectors were tuned to listen for hydrogen atoms, while the other two listened for fluorine atoms. They placed this probe inside a powerful magnet and ran the samples through the system. Without their new chip, the machine would have needed four separate cables to send the data to the computer. Instead, the chip combined all four signals into one cable. The results showed that the system worked remarkably well. The computer was able to separate the signals again and produce clear spectra for all four samples simultaneously. While there was a slight drop in signal clarity for some channels, ranging from about 8 percent to 32 percent, the researchers found that simply repeating the measurement and averaging the results could restore the quality. When they averaged 32 scans, the signal quality improved by a factor of more than five, nearly reaching the theoretical limit expected for such a process.

To further prove the flexibility of their design, the team conducted a second experiment using a different probe that held a single sample but contained two coils tuned to different types of atoms: hydrogen and carbon. This setup allowed them to test if the chip could handle signals from different elements at the same time. They ran the experiment in a slightly smaller magnet and again combined the two signals into one cable. The results confirmed that the chip could successfully manage signals from different atomic nuclei, even though they vibrate at very different frequencies. The signal quality remained high, with only a tiny loss of clarity for the hydrogen signal and an almost imperceptible loss for the carbon signal. By averaging 16 scans, they again recovered the signal strength almost completely, demonstrating that the system is stable enough for long-term experiments.

One of the most significant advantages of this new method is how it saves time. In a traditional setup, if a scientist wanted to run 32 measurements on four different samples, they would have to wait for the machine to finish one sample, then the next, and so on, repeating the process four times. With the multiplexed system, all four samples are measured at the same time during those 32 cycles. This means the total time required for the experiment is cut down by a factor of four, a massive gain for high-throughput work like drug discovery. The researchers also demonstrated that the system could handle complex pulse sequences, such as those used to measure how long it takes for a signal to return to its resting state, without losing stability. They even showed that they could use software to clean up any minor interference between the channels, ensuring that the data from one sample did not bleed into the data of another.

The success of this work suggests that the future of nuclear magnetic resonance spectroscopy could involve much denser arrays of detectors packed into smaller spaces. Because the chip is so small and integrates so many functions, it can be placed very close to the sample, reducing the loss of signal that usually happens when electricity travels through long wires. The researchers noted that while their current chip was made using a standard manufacturing process, future versions could be made with even smaller features, allowing for even more channels to be packed onto a single device. This could eventually lead to spectrometers that can analyze dozens of samples at once, transforming how scientists approach large-scale chemical screening. The study confirms that it is possible to bypass the traditional limitations of bulky, multi-cable systems, offering a practical path toward faster, more efficient, and more affordable chemical analysis.