There are different types of smart materials that are used in engineering and technology. Some common types include: 1. Shape memory alloys: These are materials that can change shape when heated or exposed to a magnetic field. They are used in applications such as biomedical devices, robotics, and aerospace engineering. 2. Piezoelectric materials: These materials generate an electric charge when mechanically deformed, and vice versa. They are used in sensors, actuators, and energy harvesting devices. 3. Electroactive polymers: These are materials that can change shape or size when an electric field is applied to them. They are used in applications such as artificial muscles, sensors, and energy harvesting devices. 4. Magnetostrictive materials: These materials change their shape or size when exposed to a magnetic field. They are used in sensors, actuators, and energy harvesting devices. 5. Thermoelectric materials: These materials can convert thermal energy into electrical energy, and vice versa. They are used in applications such as power generation, waste heat recovery, and thermal imaging. 6. Self-healing materials: These materials can repair cracks or damage on their own, without the need for external intervention. They are used in applications such as coatings, composites, and structural materials.