Laser Activated Microrobots To Deliver Drug Therapy

The microrobot concept is really cool because you can get micromachinery right to where you need it. Micro- and nanorobots that can be navigating into hard-to-reach tissues have drawn extensive attention for the promise to empower various biomedical applications; such as disease diagnosis, targeted drug delivery, and minimally invasive surgery.

It could be drug delivery, or a predesigned microsurgery. The microrobot consist of microscopic spheres of magnesium metal coated with thin layers of gold and parylene; a polymer that resists digestion. The layers leave a circular portion of the sphere uncovered, kind of like a porthole.

The uncovered portion of the magnesium reacts with the fluids in the digestive tract; generating small bubbles. The stream of bubbles acts like a jet and propels the sphere forward until it collides with nearby tissue. As magnesium spherical microrobots that can zoom around might be interesting, but they are not especially useful. To turn them from a novelty into a vehicle for delivering medication.

Microrobot drug delivery

However, the infrared laser light diffuses through tissues; and is absorbing by oxygen-carrying hemoglobin molecules in red blood cells; causing the molecules to vibrate ultrasonically. Those ultrasonic vibrations are picking up by sensors pressing against the skin.

The data from those sensors is used to create images of the internal structures of the body. With respect to the microrobots, the technique has two jobs. The first is imaging. By using PACT, the researchers can find tumors in the digestive tract and also track the location of the microrobots, which show up strongly in the PACT images.

Bubble jets activation

Once the microrobots arrive in the vicinity of the tumor, a high-power continuous wave near infrared laser beam is used to activate them. Because the microrobots absorb the infrared light so strongly, they briefly heat up, melting the wax capsule surrounding them, and exposing them to digestive fluids.

At that point, the microrobots bubble jets activate, and the microrobots begin swarming. These micromotors can penetrate the mucus of the digestive tract and stay there for a long time. This improves medicine delivery. The jets are not steerable, so the technique is sort of a shotgun approach the microrobots will not all hit the targeted area, but many will.As a major incarnation of PAT, PA computed tomography (PACT) has attained high spatiotemporal resolution (125-μm in-plane resolution and 50-μs frame−1 data acquisition), deep penetration (48-mm tissue penetration in vivo), and anatomical and molecular contrasts