Patent Application
20150142324
In vascular plants [Wunderlin, R. P., 2002], xylem is one of the two types of transport tissue, phloem being the other one (in
(i) Transpirational Pull: The most important cause of xylem sap flow is caused by the evaporation of water from the surface mesophyll cells to the atmosphere. Leaves play a major role in transpiration process. This transpiration causes millions of minute menisci to form in the cell wall of the mesophyll. The resulting surface tension causes a negative pressure in the xylem that pulls the water from the roots and the soil.
(ii) Root Pressure: If the water potential of the root cells is more negative than the soil, usually due to high concentrations of solute, water can move by osmosis into the root. This may cause a positive pressure that will force sap up the xylem towards the leaves. In extreme circumstances the sap will be forced from the leaf through a hydathode in a phenomenon known as guttation. Root pressure is most common in the morning before the stomata open and cause transpiration to begin. Different plant species can have different root pressures even in a similar environment.
Phloem is normally the inner tissue of stem and its main function is to transport sugars and other food materials from the leaves, where they are produced, to all other parts of the plant. This could be from the leaves to the roots to provide the chemicals needed for growth. However, it could be from a leaf and up to a developing fruit that is rich in sugars. The sugars are made by photosynthesis, which occurs in green parts of plants, such as leaves. The amino acids are made from sugars and minerals, such as nitrate absorbed from the soil. Phloem tissue is usually found close to the other transport tissue in plants, xylem, which transports water and minerals. In non-woody plants phloem and xylem are found in bundles, such as the veins of a leaf.
Phloem is composed of various specialized cells. It is composed of sieve elements and their associated companion cells, together with some sclerenchyma and parenchyma cell types. Sieve elements are long, thin-walled cells joined end to end, forming sieve tubes; large pores in the end walls allow the continuous passage of organic nutrients in particular, sucrose, a type of sugar that a plant need in all parts.
The transport tissues i.e. xylem and phloem, primarily flow vital liquids called sap that contains sugars, nitrates, water and ionized inorganic materials of chemical compounds. This ionic concentration is used to determine pH levels of sap. It is very important to know plants health by determining condition of pH and ionic contents of minerals.
Green plants are unable to live without sunlight. Photosynthesis is the process by which plants use the energy from sunlight to produce sugar, which is then converted into chemical forms of energy that can be used by biological systems. During this process, plants convert carbon dioxide (CO2) into organic material through the reduction of this gas into carbohydrates. The initial energy for this process is provided by the light of the sun, which is absorbed by pigments like chlorophylls and carotenoids. These chlorophylls absorb mostly blue and red light, while the carotenoids absorb blue-green light. Green and yellow light are not absorbed by the photosynthetic pigments in plants; therefore, these light colors are reflected by or passed through the leaves. This is why plants are usually green [Starr, F. and Martz, K., 1999].
Basically, Photosynthesis is the process when a plant turns the energy that it gets from the Sun into energy that the plant can use. When a plant has more sunlight it can photosynthesize faster because there is more sunlight for the plant to convert into energy. It is also important because it provides the energy that causes available water and carbon dioxide to react.
It is important to know soil forming contents, especially the concentration of soluble minerals which the plants' root can absorb. It is determined that the amount of these soluble minerals can be determined by measuring the ionic concentration in moisture or water in soil.
Electronic systems [Roden, M. S., 2002] today are used in many applications in biology. A new system is designed here to determine various vital information about the plant that are related to soil condition such as moisture, ionic concentration, sunlight intensity and plants transport tissue condition of sap. Four different types of sensors are used primarily to determine the relationship that is important to know about the plant.
Temperature Sensor: A very common sensor called ‘Thermistor’ is used in this project. Resistivity of sensor changes due to temperature is very linear; thus makes it a very simple attachment to the electronic circuits for the temperature sensing applications.
CdS Light Sensor: Light sensor of the system is very important for understanding the condition of active photosynthesis process in the leaves. During food processing, sucrose (glucose) and amino acid (protein) is produced in the green leaves of plants depending on the light intensity.
Soil Moisture Sensor: It is a very important part of the electronic system. Soil moisture and available ionic concentration depends on the amount of water in the soil. Soil's ionic concentration is determined a set of sensor probes in the soil. The electron permittivity is then measured to determine the available ions relative to soil moisture. Also longer period of electron injection can determine the steady-state soil conductance by changing ionic state of the minerals (in
Stem Sap Sensor: This special sensor is made of very hard carbon-based ceramic compound. It is also very sensitive to any small amount of ions in the sap that are touching on the surface of the sensor probes during sap flow in the stem of the plant. These probes are inserted in plant stem at least a distance of 10 cm from each other. So the differential state of ionic presence on probes due to the distance in stem can be used as a factor of ionic concentration of minerals in the plant's sap. This specially designed sensor is 0.6 mm×0.6 mm×7.5 mm long and used in the samples of Epipremnum pinnatum, i.e. Money plants. The sensor can also be designed based on the species of plant, and also its stem type and area.
Processing Unit: This is a small electronic processing unit [Sterpone, L., 2008] consisting of two IC (integrated circuits) chips. This circuit receives the analogous signals from sensors through copper wires that are specially insulated with micro-thin enamel. Wires are connected to ceramic sensor probes by application of special conductive gel compound. This unit produces combined information which later can be used for the plant's vital sign. Latter the combined information is used for producing audible beats, ion charge density and electron injection factors for conversion to conductance.
Health-beat Generator: A small electronic module that is attached to the sensor data processing unit. This module transforms the processed information into a relative frequency that is converted into heartbeat like sound by a tiny speaker. So the sound can be fast or slow paced based on the processed information as the plant's vital sign after system tuner adjustments.
Electron injection is done by applying a low DC potential at ultra-low current levels. Injection process was done using a large capacitor 4700 uf to verify charge collection process based on time (in
The second set of circuit, built with another IC, was connected to the sensors placed 10 cm apart (in
Light condition was measured by a simple CdS photo sensor connected to the system by the tuned signal amplifier. Similarly, a common thermistor sensor was incorporated with an amplifier for the system to monitor temperature, a factor for soil ion concentration and transpiration of plants.
After collecting all sensors data, final tuning adjustments were made to all system circuits as necessary. These adjustments were completed after correlating with pH, light and moisture meters bought from a local plant nursery. Thus the system was made ready to run the experiments for the plant after confirming its operational flow (in
Plant's status was determined in few simultaneous data collection steps after watering the plant. These data were later plotted to understand the state and process of transpiration of plant related to the soil moisture level (in
All data external to the plant were conductance, moisture and temperature; but they were very important information for determining the plant's sap condition, additional to the information that were collected by the sensor probes placed in the stem. Processing of the system is completed using the information generated by its respective amplifier circuits. An output signal generated by the system is then processed for an audible sound similar to an animal heartbeat. The system can generate a variable beat made by the processing status of the sap condition. As plants do not have heart, but their sap condition determines their living condition or vital status; the reason why this heartbeat like sound is called as ‘health-beat’ in this work.
A typical equation is expressed by,
F(t)=Healthbeat signal bit-rate
S(f)=Continuous signal at output
f=Averaging process of signal peak
φ(s)=Sensor's electronic specification value at linear region
k=Independent variables i.e. Soil, Sap, Stem growth etc.
s=Dependent variables of sensors i.e. moisture, solute ion, sap ion and flow, temperature, light
M(s)=Sensor pre-amp tuning factor
Y(k)=Factorizing-combinational value
Z(t)=Healthbeat signal timing factor
dT/dt=Change in temperature at any given time as required on daily, seasonal or annual basis
Note: parametric values and their characteristics can change based on the requirements of the system; thus the equation be altered.
This section lists the main features of the system. Other features are described in the subsequent sections. These features are:
A sensing amplifier was designed for a carbon-based ceramic sensor consisting 3 probes having dimension of 4 mm×4 mm×60 mm were used in the first successful test of plant sap information of a young Live Oak tree i.e. Quercus virginiana, having 12 ft height in September 2011.
Various experiments continued including vegetables and Rose plants using various dimensions of probes and amplifier circuits.
During the months between May and September 2012, the best successful designs of amplifiers were tuned to factorizing-combinational circuit input setup. In October, the first successful system was used to collect data and verified the healthbeat of home grown common Money plant i.e. Epipremnum pinnatum cv. Aureum.
