Microelectromechanical system (MEMS) devices, such as accelerometers, are widely used across industries, including the automotive, consumer electronics, and medical industries. MEMS are efficiently produced at very high volumes using large-scale semiconductor manufacturing techniques. However, these techniques are not viable for the costefficient manufacturing of specialized MEMS devices at low- and medium-scale volumes. Thus, applications that require custom-designed MEMS devices for markets with low- and medium-scale volumes of below 5000-10,000 components per year are extremely difficult to address efficiently. The 3D printing of MEMS devices could enable the efficient realization and production of MEMS devices at these low- and medium-scale volumes. However, current micro-3D printing technologies have limited capabilities for printing functional MEMS. Herein, we demonstrate a functional 3D-printed MEMS accelerometer using 3D printing by two-photon polymerization in combination with the deposition of a strain gauge transducer by metal evaporation. We characterized the responsivity, resonance frequency, and stability over time of the MEMS accelerometer. Our results demonstrate that the 3D printing of functional MEMS is a viable approach that could enable the efficient realization of a variety of custom-designed MEMS devices, addressing new application areas that are difficult or impossible to address using conventional MEMS manufacturing.

Holes through silicon substrates are used in silicon microsystems, for example in vertical electrical interconnects. In comparison to deep reactive ion etching, laser drilling is a versatile method for forming these holes, but laser drilling suffers from poor hole quality. In this article, water is used in the silicon drilling process to remove debris and the shape deformations of the holes. Water is introduced into the drilling process through the backside of the substrate to minimize negative effects to the drilling process. Drilling of inclined holes is also demonstrated. The inclined holes could find applications in radio frequency devices.

The functional area of silicon-based MEMS devices often occupies only a fraction of the actual silicon area of the chip. As the chip cost directly scales with the total chip area, there is an incentive to reduce the chip to the smallest possible size. However, handling such diminutive devices poses challenges that industry-standard packaging cannot solve. Here, we manufactured and packaged the world’s smallest spray nozzle chip for drug delivery to the lung and demonstrated how magnetic assembly combined with microfluidic glue fixation can overcome this barrier for diminutive MEMS devices. The spray nozzle chips have a circular footprint with a diameter of 280 μm and feature a nickel coating on their conical sidewall, allowing magnetic manipulation. The chips are assembled and sealed into plastic substrates using a three-step gluing process guided by capillary action and activated by heat. We demonstrate assembly speeds of up to 91 chips per minute and show this device from fabrication to packaging and functional operation for the target application.