Integrated Capacitive Ultrasonic Probe with On-Chip Bias Condenser
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Solution Overview
Problem
Ultrasonic examination devices using capacitive ultrasonic transducers face challenges with direct current bias voltage leakage and short circuit breakdowns, particularly in blood vessel catheters, where parasitic capacitance between separate semiconductor chips leads to rapid discharge of electric charge, making long-term operation difficult and increasing the risk of current leakage into the body.
Innovation Solution
Integrating a capacitive type cell and a charging condenser in a single semiconductor chip, connected in parallel, with a switch to control the DC bias power source, allowing the charging condenser to supply direct current voltage to the transducer, reducing parasitic capacitance and preventing continuous current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a battery or condenser is mounted in a separate semiconductor chip from the ultrasonic transducer, then the direct current bias voltage can be supplied to the transducer, but great parasitic capacitance occurs between the separate chips causing rapid charge discharge and preventing long-term operation
Solution Approach 1:
The patent merges the ultrasonic transducer and the condenser into a single integrated semiconductor chip structure. The transducer includes a first condenser with first and second electrodes, and a second condenser with third and fourth electrodes, all fabricated on the same chip. This integration eliminates the parasitic capacitance between separate chips while maintaining the ability to supply direct current bias voltage to the transducer through the second condenser.
Solution Approach 2:
The semiconductor chip serves multiple functions simultaneously: it acts as both the ultrasonic transducer structure and the power storage element. The first condenser provides the ultrasonic transduction function, while the second condenser provides the direct current bias voltage storage function, both within the same chip entity, eliminating the need for separate power supply chips.
2Ease of manufacture
If a separate semiconductor chip is used for the condenser and ultrasonic transducer, then manufacturing flexibility is improved, but the device size increases and miniaturization is hindered
Solution Approach 1:
The patent combines multiple functional elements (ultrasonic transducer and condenser) into a single semiconductor chip, reducing the overall device volume. The first and second condensers are fabricated on the same chip substrate, eliminating the need for separate power supply chips and enabling probe miniaturization while maintaining manufacturing feasibility through standard integrated circuit fabrication processes.
3Ease of operation
If direct current voltage is continuously applied to the ultrasonic transducer, then proper operation is maintained, but the risk of current leakage into the body increases when short circuit breakdown occurs
Solution Approach 1:
The second condenser acts as an intermediary energy storage element between the direct current power source and the ultrasonic transducer. It charges to a predetermined voltage and then supplies the bias voltage to the transducer, isolating the transducer from direct connection to high-voltage DC sources. This intermediary structure reduces the risk of current leakage into the body while maintaining proper transducer operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the performance and longevity of the ultrasonic examination device by reducing parasitic capacitance, preventing current leakage, and enabling miniaturization of the ultrasonic probe, while ensuring safe operation by isolating the direct current voltage from the semiconductor chip.
Implementation Method 1
vibrating a membrane (flexible film) in the vicinity of a resonance frequency
Implementation Method 2
Related-art ultrasonic sensors normally use oscillation of a piezoelectric substance
Implementation Method 3
a charging condenser, the cell and the charging condenser being mounted in one semiconductor chip and being connected with each other in parallel
Data Source
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AI summary
Performance of an ultrasonic examination device, which includes an ultrasonic sensor of a capacitance detection type including a cavity between electrodes and vibrating a membrane, is enhanced. A cell 2 which is a capacitive type device provided with a lower electrode 8, a cavity 10, and an upper electrode 6 in a membrane 12, which are stacked in a longitudinal direction, and a condenser 5 provided with the lower electrode 8 and an upper electrode 7 which are stacked in the longitudinal direction, are formed in one semiconductor chip. The cell 2 and the condenser 5 are connected to each other in parallel, and, when ultrasonic waves are transmitted and received using the cell 2, connection between a DC bias power source and the semiconductor chip is blocked, and a direct current voltage is applied to the cell 2 from the condenser 5.