Time of Flight Sensor with a Flow Parallel Wire
A time of flight sensor has been equipped with a sensing wire parallel to the flow direction (flow parallel wire, FPW). A heat pulse is generated with a coil in the flow channel. The FPW has a center tap allowing its upstream and downstream parts to join in a half bridge. When a heat pulse passes the FPW, a large output peak is generated. The time between heat pulse generation and recording the peak maximum is only marginally affected by the properties of the fluid. With a combination of two FPWs, a measuring range of approximately 0.01–0.5 m/s can be achieved.
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.
A microfluidic system for the measurement of chemical concentration and density
A new microfluidic system for measuring chemical concentration, fluid density and specific gravity has been developed. Measurements can be made with under a microliter of sample fluid, which is over 1000 to 3000X less than that required in conventional systems. Since the product is MEMS-based the overall system size is a fraction of conventional fluidic density meters and it weighs much less (1kg vs. 20kg) than traditional desk-top, temperature controlled, density meters. The syringe or pipette loaded system includes a dynamic temperature control system employing thermoelectric panels that operates between 0/spl deg/C and 90/spl deg/C with a temperature accuracy of less than 0.01/spl deg/C and better than 4-digit fluidic density resolution. In order to obtain this temperature and hence density accuracy an on-chip temperature sensor was added to the MEMS chip. Also a new method of chip-level gettering was developed to achieve the sub-milliTorr pressures needed for adequate resonator signal quality.