This paper proposes a classification scheme for the quantified analysis of micro-grip principles. Micro-part gripping has received quite some attention in micro-assembly research. However, there is a lack of quantified data on the characteristics and applicability of micro-grip principles. The micro-grip principle is the physical principle that produces the necessary forces to get and maintain a part in a position with respect to the gripper. The classification scheme defines criteria that are essential in the evaluation and selection of a micro-grip principle for gripping a given part. The criteria are defined on the basis of characteristics of the parts to be gripped, demands on the grip operation to be performed and characteristics of the environment in which the grip operation takes place. The classification scheme is evaluated using examples from literature.

Microvalves are important flow-control devices in many standalone and integrated microfluidic applications. Polydimethylsiloxane (PDMS)-based pneumatic microvalves are commonly used but they generally require large peripheral connections that decrease portability. There are many alternatives found in the literature that use Si-based microvalves, but variants that can throttle even moderate pressures (1 bar) tend to be bulky (cm-range) or consume high power. This paper details the development of a low-power, normally-open piezoelectric microvalve to control flows with a maximum driving pressure of 1 bar, but also retain a small effective form-factor of 5 mm × 5 mm × 1.8 mm. A novel combination of rapid prototyping methods like stereolithography and laser-cutting have been used to realize this device. The maximum displacement of the fabricated piezoelectric microactuator was measured to be 8.5 μm at 150 V. The fabricated microvalve has a flow range of 0–90 μL min⁻¹ at 1 bar inlet pressure. When fully closed, a leakage of 0.8% open-flow was observed with a power-consumption of 37.5 μW. A flow resolution of 0.2 μL min⁻¹—De-ionized (DI) water was measured at 0.5 bar pressure.

This paper presents two integrated piezoresistive sensors capable of detecting simultaneously both the contact force and the contact position of a micro-object in micro-handling applications. The first sensor detects the 1-D contact position in vertical direction along a contact surface. The second sensor extends the sensing principle and detects the contact position on a 2-D contact surface. The devices combine the outputs of two groups of piezoresistors in Wheatstone bridge configurations, allowing the computation of the contact force and the contact position. The sensors are fabricated with an IC-compatible process and can be integrated in micro-handling tools such as micro-grippers. The two devices are characterized by applying forces onto the contact surface at pre-defined positions. With an applied contact force ~ 1 mN, the first sensor has a force resolution of 1 μN and a vertical position detection accuracy of 2-3 μm. The estimated force range detectable is 3 mN and a sensitivity of 2.8 V/N is obtained with an effective supply voltage of 177 mV across the Wheatstone bridge. The second sensor has a force detection range up to 3 mN with a resolution of 20 μN under a measured noise of 30 μV. The theoretical spatial resolution is ~ 5μm in both x and y directions with a contact force of 1 mN. The devices are designed to handle micro-objects with sizes of 25-250 μm. The concept and the principle of the device are not limited to applications in micro-grippers and can be used in other micro-handling tools.