Recipient Organization
LW Microsystems, Inc
(N/A)
Fremont,CA 94536
Performing Department
(N/A)
Non Technical Summary
The currently available watermelon ripeness test equipment is space consuming (which may occupy a desk table), and expensive (>$1000/each), thus, prevent it to be widely used by watermelon farmers and general consumers. This proposal is submitted for research on using micro electro-mechanical systems (MEMS) technology to make small size, low cost watermelon ripeness testers in the application of watermelon ripeness detection for both watermelon consumers and farmers.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The overall objective of this project is to develop small size, low cost watermelon freshness/ripeness testers in the application of watermelon ripeness detection for both watermelon consumers and farmers. The specific objective in Phase I is using MEMS technology to develop OMV sensors, which detect response frequencies (e.g., 100, 150, and 200 Hz) of ripe watermelons. The research on freshness melon sensor will be conducted in Phase II of the project. The OMV sensor is the core device of the watermelon ripeness tester. The details of the objective include establishing the material, structure, and dimensions of the OPV sensor. The questions that will be addressed to determine the technical and commercial feasibility of the OMV sensor for watermelon ripeness detecting are as follows: 1. What is the overall size of the OMV sensor, which is robust, and sensitive enough to detect the response vibration of a tested melon? 2. What is the intensity of the tap from a tapper,
which is high enough to activate the OPV sensor without generate too much noise (or skin vibrations) and damage the tested watermelon? 3. What is the correction factor K in equations 1 and 2? 4. What are the best materials to build OMV sensors? 5. What are the best dimensions (e.g., thickness, width and length) of oscillating plates and hinges for testing 100, 150, and 200 Hz frequencies? 6. What is the best process to achieve the design? 7. Will the OMV sensor sense the response vibration of a tapped watermelon? The answers to these questions will establish the technical and commercial feasibility of developing a watermelon ripeness tester that will overcome the limitations of tradition watermelon ripeness testing approaches and enhance its properties cost effectively. The Phase I demonstration of this paradigm sensor will provide basis for Phase II investigation, optimization and demonstration of a watermelon freshness/ripeness sensor. These Phase II demonstrations will provide the
basis for Phase III commercialization, which will be performed in concert with grocery suppliers.
Project Methods
LW Microsystems will use MEMS techniques to make watermelon ripeness tester. During watermelon ripeness measurement, we only concern certain vibration frequency (which corresponds to ripe watermelons) in response to a tapping, i.e., ripe vibration frequency (RVF). Thus, we propose to develop a set of fixed vibration frequency sensors corresponding to RVFs of melons. The fixed frequency vibration sensor is the core element in the ripeness tester, which will be made using MEMS technique. The fixed frequency vibration sensor will be designed and fabricated for detecting the vibration frequencies corresponding to most common types of ripe watermelons in the market. In the proposed watermelon ripeness detecting process, a mechanical tapper will tap the watermelon with a fixed force, and the response vibration frequency will be measured with the fixed frequency vibration sensor. Once the watermelon vibration frequency matches the RVF, indication window of the sensor will
flash, indicating the measured watermelon is ripe. Micro vibration sensors based on MEMS technique are employed in some of the prior art, e.g., in acceleration detectors for automobile applications. An on-chip vibration sensor is typically used to detect motion in acceleration detections. There are two types of commonly used MEMS vibration sensors in acceleration detectors, i.e., piezoresistor and capacity sensors. Both sensors are fabricated through a series of complicated semiconductor processes, and also need signal analyzers or processors to convert electronic signal into usable data output, thus increases the cost and space of the sensor system. In contrast, our approach simplifies the design by eliminating the on-chip piezoresistor or capacity sensors, thus reduces the fabrication cost. LW Microsystems sensor utilizes the resonance frequency of the sensor structure, and provides a signal output whenever the measured vibration matches the structure resonance frequency. The
proposed sensor consists of a light beam source #1, a two-hinge oscillating mirror #2, a substrate #3, a light monitor window #4 and a solid supporting structure #5. At standstill (standby) condition, the light beam#1, the oscillating mirror #2 and the monitor window #4 are aligned in the way that reflection light from oscillating mirror #2 is directed away from the monitor window #4. No light is observed from the monitor window. The oscillating mirror deploys two hinges that support the mirror. The stiffness/structure of hinge and mass of the mirror determine the resonant frequency of the mirror movement. During measurement application, when the frequency of outside vibration source matches the oscillating plate resonant frequency, the plate #2 starts constant oscillating around the hinges thus the reflected light beam from oscillating mirror #2 scans the monitor window #4. The substrate #3 is used to limit the oscillating mirror movement from over torque and broken. Once the
indication window flash, we know the outside vibration source has the same frequency as the resonant frequency of mirror. An oscillating mirror is designed to measure only a certain frequency.