IISc scientists develop new way to move quantum sensors

Bengaluru: Researchers at the Indian Institute of Science (IISc) have developed a novel method to guide tiny quantum sensors through thick, gel-like environments such as the interior of living cells.

The breakthrough could allow scientists to measure conditions like temperature and viscosity inside cells in real time without causing damage. In the future, this may help detect key biological markers, including those linked to cancer and ageing.

Studying the inner workings of cells has long been a challenge due to their soft and crowded nature. Extremely small particles, including quantum sensors, struggle to move freely because of resistance from the surrounding fluid.

According to Ambarish Ghosh, Professor at the Centre for Nanoscience and Engineering (CeNSE), this limits the chances of sensors coming into contact with the substances they are meant to measure. “Instead of waiting for the target to come to the sensor, we asked if we could take the sensor to the target,” he said.

To address this, the team attached a nanodiamond-based sensor to a tiny magnetic microbot. The sensor emits light when stimulated by a laser, and changes in this light reveal details about its surroundings, such as temperature or magnetic fields. Earlier techniques relied on strong laser beams to move such sensors, which risked damaging delicate cells.

The IISc team’s approach avoids this issue. The microbot, made partly of iron, can be steered using an external magnetic field. Its spiral, corkscrew-like design enables it to move forward when rotated, allowing precise control in three dimensions. Light is used only during measurement, reducing the risk of heating or harming the cell.

At such small scales, another challenge is Brownian motion — the constant random movement caused by surrounding molecules — which can interfere with readings. By controlling the microbot magnetically, the researchers were able to stabilise the sensor and improve accuracy.

The team also ensured that the magnetic components did not affect the sensor’s performance by placing the nanodiamond at a safe distance from the microbot’s iron head.

The study has been published in Advanced Functional Materials.