To realize an efficient translation in a narrow space, a surface milli-walker based on linear piezoelectric actuation is proposed, fabricated, and tested. Operating at the second order out-of-plane flexural vibration mode, the proposed surface walker is able to realize a linear movement on demand. The surface walker has a weight of only 0.135 g with package size of 6 mm × 2 mm × 2 mm. Experimental results show that the maximum velocity and drag force of the walker can reach up to 200 mm/s and 10 mN, respectively. The velocity of the walker can be smoothly adjusted over a range of 0.15 mm/s to 200 mm/s. In addition, its startup time is as quick as 6 ms. The milli-walker holds great promises for numerous potential applications in precise instruments.

Endotoxin is a deadly pyrogen, rendering it crucial to monitor with high accuracy and efficiency. However, current endotoxin detection relies on multistep processes that are labor-intensive, time-consuming, and unsustainable. Here, we report an aptamer-based biosensor for the real-time optical detection of endotoxin. The endotoxin sensor exploits the distance-dependent scattering of gold nanoparticles (AuNPs) coupled to a gold nanofilm. This is enabled by the conformational changes of an endotoxin-specific aptamer upon target binding. The sensor can be used in an ensemble mode and single-particle mode under dark-field illumination. In the ensemble mode, the sensor is coupled with a microspectrometer and exhibits high specificity, reliability (i.e., linear concentration to signal profile in logarithmic scale), and reusability for repeated endotoxin measurements. Individual endotoxins can be detected by monitoring the color of single AuNPs via a color camera, achieving single-molecule resolution. This platform can potentially advance endotoxin detection to safeguard medical, food, and pharmaceutical products.

Micro robots, due to their light weight, small size and high mobility, can explore narrow space or hazardous locations that humans or larger robots cannot reach. Consequently, both academia and industry are concerned with the development of advanced microrobots. In this paper, we design a steerable miniature legged robot (SMLR) which possesses light weight and controllable linear/steerable motion by using two piezoelectric bending actuators. Its dimensions are 35 mm × 30 mm × 9 mm (length × width × height) and mass is 9 g. User can modulate the speed, turning radius, and load capacity of the robot by simply tuning the driving voltage. The robot exhibits a speed of 330 mm s ⁻¹ and a turning radius of 102 mm upon a driving voltage of 200 V and a frequency of 8.67 kHz. Moreover, it is capable of driving a 55 g embedded mass at a speed of 20 mm s ⁻¹ under a voltage of 200 V, and its simple design is ideal for down-sizing. Further, we establish a series of open-loop control programs in a virtual instrument through LabVIEW to accurately control the behavior of the SMLR (the location error is less than 5 mm), demonstrating its great potential in practical applications such as movement in a narrow space.

With over a million cases detected each year, skin disease is a global public health problem that diminishes the quality of life due to its difficulty to eradicate, propensity for recurrence, and potential for post-treatment scarring. Photodynamic therapy (PDT) is a treatment with minimal invasiveness or scarring and few side effects, making it well tolerated by patients. However, this treatment requires further research and development to improve its effective clinical use. Here, a piezoelectric-driven microneedle (PDMN) platform that achieves high efficiency, safety, and non-invasiveness for enhanced PDT is proposed. This platform induces deep tissue cavitation, increasing the level of protoporphyrin IX and significantly enhancing drug penetration. A clinical trial involving 25 patients with skin disease was conducted to investigate the timeliness and efficacy of PDMN-assisted PDT (PDMN-PDT). Our findings suggested that PDMN-PDT boosted treatment effectiveness and reduced the required incubation time and drug concentration by 25% and 50%, respectively, without any anesthesia compared to traditional PDT. These findings suggest that PDMN-PDT is a safe and minimally invasive approach for skin disease treatment, which may improve the therapeutic efficacy of topical medications and enable translation for future clinical applications.