Powerless Liquid Transfer System Combining Vacuum Chamber and Constant Flow Rate Valve with Laminated Structure of PMMA Plates and PDMS Membrane

A powerless liquid transfer system for wearable skin microperfusion was fabricated. In our previous work, minimally invasive microperfusion needle which collects biological substances from subepidermal tissue had been developed. The liquid transfer system for skin microperfusion requires low flow rate, constant flow rate, low power driven, disposability, and small size. The fabricated powerless liquid transfer system is driven by a combination of a passive constant flow valve with a PDMS membrane laminated between PMMA plates, and a vacuum chamber. The fabricated liquid transfer system has a flow rate of less than 5 µl/min (fluctuations were less than 1 µl/min) for more than 120 minutes. In addition, this liquid transfer system was possible to meet the required specifications even when a fluid resistor was inserted to simulate the same level of pressure drop as the microperfusion needle and sensor.